China's new radio telescope, the world's largest, should be completed by September 2016. Image: FAST
China is building the world’s largest radio telescope, and will have to move almost 10,000 people from the vicinity to guarantee the telescope’s effectiveness. The telescope, called the Five-hundred-meter Aperture Spherical Telescope (FAST), will be completed in September, 2016. At 500 meters in diameter, it will surpass the workhorse Arecibo radio observatory in Puerto Rico, which is 305 meters in diameter.
China has routinely moved large amounts of people to make room for developments like the Three Gorges Dam. But in this case, the people are being moved so that FAST can have a five kilometre radio-quiet buffer around it.
According to China’s news agency Xinhua, an unnamed official said the people are being moved so that the facility can have a “sound electromagnetic wave environment.” Common devices and equipment like microwave ovens, garage door openers, and of course, mobile phones, all create radio waves that FAST will sense and which can interfere with the telescope’s operation.
The telescope’s high level of sensitivity “will help us to search for intelligent life outside of the galaxy,” according to Wu Xiangping, director-general of the Chinese Astronomical Society. But aside from searching for radio waves that could be from distant alien civilizations, like SETI does, the enormous dish will also to be used to study astronomical objects that emit radio signals, like galaxies, pulsars, quasars, and supernovae. The radio signals from these objects can tell us about their mass, and their distance from us. But the signals are very weak, so radio telescopes have to be huge to be effective.
Radio telescopes are also used to send out radio signals and bounce them off objects like asteroids and the other planets in our Solar System. These signals are detected by the telescope when they return to Earth, and used to create images.
Huge radio telescopes like FAST can only be built in certain places. They require a large, naturally dish-shaped area for construction. (Arecibo is built in a huge karst sinkhole in Puerto Rico.) Though FAST is in a fairly remote location, where there are no major cities or towns, there are still approximately 10,000 people who will have to be moved. Most of the people moved will be compensated to the tune of $2500, with some receiving more than that.
The FAST facility is part of a concerted effort by China to be a dominant player in space study and exploration. The Chang e 3 mission to the Moon, with its unmanned lander and rover, showed China’s growing capabilities in space. China also plans to have its own space station, its own space weather station at LaGrange 1, and a mission to Mars by 2020, consisting of an orbiter and a rover.
Construction on FAST began in 2011, and will cost 1.2 billion yuan ($260 million) to build.
Milky Way (without the constellations) by Matt Dieterich
Hundreds of galaxies hidden from sight by our own Milky Way galaxy have been studied for the first time. Though only 250 million light years away—which isn’t that far for galaxies—they have been obscured by the gas and dust of the Milky Way. These galaxies may be a tantalizing clue to the nature of The Great Attractor.
On February 9th, an international team of scientists published a paper detailing the results of their study of these galaxies using the Commonwealth Scientific and Industrial Research Organization’s (CSIRO) Parkes radio telescope, a 64 meter telescope in Australia. The ‘scope is equipped with an innovative new multi-beam receiver, which made it possible to peer through the Milky Way into the galaxies behind it.
The area around the Milky Way that is obscured to us is called the Zone of Avoidance (ZOA). This study focused on the southern portion of the ZOA, since the telescope is in Australia. (The northern portion of the ZOA is currently being studied by the Arecibo radio telescope, also equipped with the new multi-beam receiver.) The significance of their work is not that they found hundreds of new galaxies. There was no reason to suspect that galactic distribution would be any different in the ZOA than anywhere else. What’s significant is what it will tell us about The Great Attractor.
The Great Attractor is a feature of the large-scale structure of the Universe. It is drawing our Milky Way galaxy, and hundreds of thousands of other galaxies, towards it with the gravitational force of a million billion suns. The Great Attractor is an anomaly, because it deviates from our understanding of the universal expansion of the universe. “We don’t actually understand what’s causing this gravitational acceleration on the Milky Way or where it’s coming from,” said Professor Lister Staveley-Smith of The University of Western Australia, the lead author of the study.
“We know that in this region there are a few very large collections of galaxies we call clusters or superclusters, and our whole Milky Way is moving towards them at more than two million kilometres per hour.”
The core of the Milky Way seen in Infrared. Seeing through this has been a real challenge. Credit: NASA/Spitzer
Professor Staveley-Smith and his team reported that they found 883 galaxies, of which over one third have never been seen before. “The Milky Way is very beautiful of course and it’s very interesting to study our own galaxy but it completely blocks out the view of the more distant galaxies behind it,” he said.
The team identified new structures in the ZOA that could help explain the movement of The Milky Way, and other galaxies, towards The Great Attractor, at speeds of up to 200 million kilometres per hour. These include three galaxy concentrations, named NW1, NW2, and NW3, and two new clusters, named CW1 and CW2.
University of Cape Town astronomer Professor Renée Kraan-Korteweg, a member of the team who did this work, says “An average galaxy contains 100 billion stars, so finding hundreds of new galaxies hidden behind the Milky Way points to a lot of mass we didn’t know about until now.”
How exactly these new galaxies affect The Great Attractor will have to wait for further quantitative analysis in a future study, according to the paper. The data from the Arecibo scope will show us the northern hemisphere of the ZOA, which will also help build our understanding. But for now, just knowing that there are hundreds of new galaxies in our region of space sheds some light on the large-scale structure of our neighbourhood in the universe.
A radio dish at Owens Valley Observatory in Owens Valley California. Credit and copyright: Credit and copyright: Harun Mehmedinovic and Gavin Heffernan.
Radio dishes always evoke wonder, as these giants search for invisible (to our eyes, anyway) radio signals from objects like distant quasars, pulsars, masers and more, including potential signals from extraterrestrials. This new timelapse from Harun Mehmedinovic and Gavin Heffernan of Sunchaser Pictures was shot at several different radio astronomy facilities — the Very Large Array (VLA) Observatory in New Mexico, Owens Valley Observatory in Owens Valley California, and Green Bank Observatory in West Virginia. All three of these facilities have been or are still being partly used by the SETI (Search for the Extraterrestrial Intelligence) program.
Watch the dishes dance in their search across the Universe!
The huge meteorite streaking across the sky above Very Large Array (2:40) is from the Aquarids meteor shower. The large radio telescope at Green Bank is where scientists first attempted to “listen” to presence of extraterrestrials in the galaxy. The Very Large Array was featured in the movie CONTACT (1997) while Owens Observatory was featured in THE ARRIVAL (1996).
This video was created for SkyGlowProject.com, a crowdfunded educational project that explores the effects and dangers of urban light pollution in contrast with some of the most incredible Dark Sky Preserves in North America.
The music is by Tom Boddy, and titled “Thoughtful Reflections.”
Thanks to Gavin Heffernan for sharing this video.
Screenshot from the DishDance timelapse. Credit and copyright: Harun Mehmedinovic and Gavin Heffernan.
Radio observations were carried out from the Allen Telescope Array of the reputed megastructure-encompassed star KIC 8462852.
Astronomers at the SETI institute (search for extraterrestrial intelligence) have reported their findings after monitoring the reputedmegastructure-encompassed star KIC 8462852. No significant radio signals were detected in observations carried out from the Allen Telescope Array between October 15-30th (nearly 12 hours each day). However, there are caveats, namely that the sensitivity and frequency range were limited, and gaps existed in the coverage (e.g., between 6-7 Ghz).
Lead author Gerald Harp and the SETI team discussed the various ideas proposed to explain the anomalous Kepler brightness measurements of KIC 8462852, “The unusual star KIC 8462852 studied by the Kepler space telescope appears to have a large quantity of matter orbiting quickly about it. In transit, this material can obscure more than 20% of the light from that star. However, the dimming does not exhibit the periodicity expected of an accompanying exoplanet.” The team went on to add that, “Although natural explanations should be favored; e.g., a constellation of comets disrupted by a passing star (Boyajian et al. 2015), or gravitational darkening of an oblate star (Galasyn 2015), it is interesting to speculate that the occluding matter might signal the presence of massive astroengineering projects constructed in the vicinity of KIC 8462582 (Wright, Cartier et al. 2015).”
One such megastructure was discussed in a famous paper by Freeman Dyson (1960), and subsequently designated a ‘Dyson Sphere‘. In order to accommodate an advanced civilisation’s increasing energy demands, Dyson remarked that, “pressures will ultimately drive an intelligent species to adopt some such efficient exploitation of its available resources. One should expect that, within a few thousand years of its entering the stage of industrial development, any intelligent species should be found occupying an artificial biosphere which completely surrounds its parent star.” Dyson further proposed that a search be potentially conducted for artificial radio emissions stemming from the vicinity of a target star.
The SETI team summarized Dyson’s idea by noting that Solar panels could serve to capture starlight as a source of sustainable energy, and likewise highlighted that other, “large-scale structures might be built to serve as possible habitats (e.g., “ring worlds”), or as long-lived beacons to signal the existence of such civilizations to technologically advanced life in other star systems by occluding starlight in a manner not characteristic of natural orbiting bodies (Arnold 2013).” Indeed, bright variable stars such as the famed Cepheid stars have been cited as potential beacons.
The Universe Today’s Fraser Cain discusses a ‘Dyson Sphere‘.
If a Dyson Sphere encompassed the Kepler catalogued star, the SETI team were seeking in part to identify spacecraft that may service a large structure and could be revealed by a powerful wide bandwidth signal. The team concluded that their radio observations did not reveal any significant signal stemming from the star (e.g., Fig 1 below). Yet as noted above, the sensitivity was limited to above 100 Jy and the frequency range was restricted to 1-10 Ghz, and gaps existed in that coverage.
Fig 1 from Harp et al. (2015) conveys the lack of radio waves emerging from the star KIC 8462852 (black symbols), however there were sensitivity and coverage limitations (see text). The signal emerging from the quasar 3c84 is shown via blue symbols.
What is causing the odd brightness variations seen in the Kepler star KIC 8462852? Were those anomalous variations a result of an unknown spurious artefact from the telescope itself, a swath of comets temporarily blocking the star’s light, or perhaps something more extravagant. The latter should not be hailed as the de facto source simply because an explanation is not readily available. However, the intellectual exercise of contemplating the technology advanced civilisations could construct to address certain needs (e.g., energy) is certainly a worthy venture.
Map showing TB145's approximate path starting at 4 hours UT on Oct. 31 (11 p.m. CDT Oct. 30). This view faces east. Tick marks show its hourly position. This map provides context for the detailed maps above. Credit: Chris Marriott's SkyMap
Trick or treat! I think we’re definitely in for a treat. 2015 TB145 will fly past Earth at a safe distance slightly farther than the moon’s orbit on Oct. 31 at 12:05 p.m. CDT (17:05 UT). Estimated at 1,300 feet (400-meters) across, this Great Pumpkin of an asteroid will be big enough and close enough to show in small telescopes.
Do I hear the doorbell ringing already?
Shining faintly at 18th magnitude on October 22, 2015 TB145 is already under study by amateur and professional astronomers. Its close approach will make for an excellent opportunity to learn a great deal about its surface properties and orbit. Watch for it to brighten up to magnitude +10.1 at peak, bright enough to see in a 4.5-inch telescope. Credit: Gianluca Masi
The close approach of such of TB145 will make for great science opportunities, too. Several optical observatories and the radar capabilities of the agency’s Deep Space Network at Goldstone, California will be tracking this flying mountain as will many amateur astronomers. The 110-foot (34-meter) Goldstone antenna will ping the asteroid with radio waves; the returning echoes will be collected by dishes in West Virginia and Puerto Rico and used to construct images showing the object’s surface features, shape and dimensions. NASA scientists hope to obtain radar images of the asteroid as fine as about 7 feet (2 meters) per pixel.
“The close approach of 2015 TB145 at about 1.3 times the distance of the moon’s orbit, coupled with its size, suggests it will be one of the best asteroids for radar imaging we’ll see for several years,” said Lance Benner, of JPL, who leads NASA’s asteroid radar research program. “We plan to test a new capability to obtain radar images with two-meter resolution for the first time and hope to see unprecedented levels of detail.”
View of the orbit of asteroid 2015 TB145. Its orbit is inclined about 39° to the plane of the Solar System. Credit: P. Chodas (NASA/JPL – Caltech)
Astronomers first nabbed asteroid 2015 TB145 on Oct. 10, 2015, using the University of Hawaii’s Pan-STARRS-1 (Panoramic Survey Telescope and Rapid Response System) telescope atop Mt. Haleakala in Maui. According to the catalog of near-Earth objectskept by the Minor Planet Center, this is the closest currently known approach by an object this large until asteroid 1999 AN10 (about 2,600 feet or 800-m in size) zips by at about 1 lunar distance in August 2027.
The gravitational influence of the asteroid is so small it will have no detectable effect on the Moon or anything here on Earth, including our planet’s tides or tectonic plates. But the planet will certainly have an effect on the asteroid. Earth’s gravity will deflect TB145’s path during the close approach, making it tricky this far out to create an accurate map of its flight across the sky. That’s why the two maps I’ve included with this article are only approximate. As we get closer to Halloween, further refinements in the asteroid’s orbit will allow for more accurate path-making.
TB145’s path starting at 4 hours UT on Oct. 31 (11 p.m. CDT Oct. 30). This view faces east. Tick marks show its hourly position. At the start of the path, the asteroid will shine around magnitude 11.4 but will gradually brighten through the night. To convert from UT, subtract 4 hours for EDT, 5 for CDT, 6 for MDT and 7 for PDT. Click for a large version. Credit: Chris Marriott’s SkyMap
Because the asteroid passes so near Earth, parallax will shift its path north or south up to 1/2°. Parallax is the apparent shift in an object’s position against the more distant background stars depending on the observer’s location on Earth. You can see how parallax works using your eyes and a finger. Stick your arm straight out in front of you and hold up your index finger. Open and close your right and then your left eye in a back and forth blinking pattern and watch your finger jump back and forth across the more distant background. Each eye sees the thumb from a slightly different perspective, causing it to shift position against the distant scene.
Graphic depicting the orbit of asteroid 2015 TB145. The asteroid will safely fly past Earth slightly farther out than the moon’s orbit on Halloween. Credit: P. Chodas (NASA/JPL – Caltech)
This happens all the time with the Moon. You might see it conjunct with a bright planet where skywatchers on the opposite side of the planet see an occultation. That’s why it’s best to make your own map of TB145’s wild ride across the sky. When closest to Earth, the asteroid will cover a Full Moon diameter about every 3 minutes as it tears by us at 22 miles per second (35 km/sec). Without a good map, it’ll get away from you.
Method #1: Using Stellarium
Download the free sky-plotting program Stellarium. Once you’ve set your location, either hit F2 or click on the Configuration icon in the lower left corner of your screen. Now select the Plugins tab then Solar System Editor. Click on Configure at the bottom of the tab, choose Solar System and click Import orbital elements in MPC format.
Next, select the Asteroids option and then from the bookmarks list, choose MPCORB: near-Earth asteroids (NEAs) and then Get orbital elements. Allow the list — a very large one — to load then scroll through it until you find 2015 TD145 and put a check mark in the box. Then click Add objects.
Stellarium view of the sky and featured asteroid seen from northern, Minnesota at 11:55 p.m. October 30, 2015. Notice that a bright, waning gibbous Moon will be nearby during the best viewing opportunities for the Americas, which will make 2015 TB145 a little harder to spot.
Still with me? OK, close the Solar System editor and press F3 or select the magnifying glass icon in the lower left corner of your screen, then type in the asteroid’s name exactly as 2015 TD145. Hit enter and you’ll see a set of rotating red crosshairs. Bingo! This where the asteroid will be at the time you chose. You can adjust your magnitude range, field of view and even download additional files of fainter stars and deep sky objects. Unfortunately, Stellarium can’t draw an arc showing TB145’s changing position with time. Cross your fingers that appears in the next iteration.
Method #2: Download up-to-date orbital elements into your sky-charting program
2015 TB145 belongs to the Apollo family of asteroids, whose orbits cross that of Earth. Amor asteroids approach but don’t cross, while Atens also cross Earth’s path but spend most of their time inside our orbit. Credit: ESA
Let’s say you already have a sky-charting program like Guide, Dance of the Planets, MegaStar or Starry Night. Go to the Minor Planet &Comet Ephemeris Serviceand type in 2015 TB145 in the big, blank box. Next, scroll down and select your program from the list and click on Get Ephemerides/HTML page. Save the file of orbital elements that pops up and place into the appropriate folder in your program. Open your program, select 2015 TB145 and make a chart!
Method #3: Manually input orbital elements into your program
You can also go to JPL’s Horizons site for the very latest orbital elements you can manually input in your program. 2015 TB145 is expected to be as bright as magnitude +10.1 (no problem in a 4.5-inch scope) but that occurs during the afternoon for the Americas. The Middle East and Asia are the place to be for closest approach. Peak brightness over the U.S. will occur before dawn on Halloween, so you can begin observation around 11 p.m. local time Friday evening October 30 when Orion comes up in the east. The asteroid starts shines at around magnitude +11-11.5 that evening and brightens overnight to around +10.3-10.5 before dawn for the Americas.
A word about tracking fast-moving asteroids. I’ve found that the best way to catch sight of one is to “camp” at the place they’ll pass at a certain time. Say you want to see TB145 at 1:15 a.m. October 31. Make a chart that shows its position every 15 minutes. Five minutes before it arrives at the 1:15 a.m. spot, point your telescope there and wait for a “moving star” to enter the field of view. If you don’t see it right way, wait a few minutes and pan around to the north and south of the location. By the way, the asteroid will pass less than a degree northwest of the Crab Nebula (M1) in Taurus around 10:30 UT (5:30 a.m. CDT).
Be aware that the bright, waning gibbous Moon will be within 10° of the asteroid when it’s best visible in the Americas. While this will make observing the asteroid more challenging, don’t let it stop you from trying. If bad weather gets in the way, Gianluca Masi has you covered. He’ll live-stream the flyby on his Virtual Telescope sitebeginning at 0:00 UT (7 p.m CDT) on October 31st.
One way or another, we’ll all have a shot at seeing the Great Pumpkin asteroid this Halloween.
2015 TB145 looks stellar in this photo taken on October 24th when it glowed at only 16th magnitude. Credit: Peter Lake
UPDATE Oct. 27, 2015: There’s been some discussion about TB145’s orbit resembling that of a comet along with speculation it might be a dead or dormant comet. Amateur and professional astronomers have been watching it closely, looking for hints of activity such as a fuzzy coma. So far, photos show the asteroid as completely stellar.
I also wanted to update you on its visibility. Those with 10-inch or larger telescopes can begin looking for the object Thursday night Oct. 29th when it reaches magnitude +13.5. The following night it leaps to +11.5 with a peak brightness of +10.0 occurring around 14:00 UT (9 a.m. CDT) on Halloween. TB145 fades rapidly thereafter – down to 15th magnitude just 8 hours later.
Situated on the south shore of New Jersey’s Shark River lies 37 acres of land known as Camp Evans. On April 1, 2015, I was privileged to attend the dedication ceremony celebrating Camp Evans’ becoming one of only 2532 locations in the United States designated as a National Historic Landmark.
In 1912, Gugliemlo Marconi and his company, the American Marconi Company, constructed the Belmar Receiving Station which became part of the wireless girdle of the earth.
In 1917, the site was acquired as part of the Navy’s World War I “Trans-Atlantic Communication System.”
In 1941, the Army Signal Corps purchased the property to construct a top-secret research facility, and it was renamed Evans Signal Laboratory which later became Camp Evans Signal Laboratory.
Following a visit in late October, 1953, Senator Joseph McCarthy described Camp Evans as a “house of spies.” Following an investigation that spanned 1953-1954, not one single employee was prosecuted.
But perhaps Camp Evans’ most interesting – and surprising – place in history begins with a small, informal research project taking place on a parcel of land in the Camp’s northeast corner. The ramifications of this project would ultimately give birth the to Space Age, lead to the development of the US Space Program, and start the Cold War.
Following the end of WWII, American scientists at Camp Evans continued their investigation into whether the earth’s ionosphere could be penetrated using radio waves – a feat that had been studied prior to the end of the War but had long been believed impossible. Project Diana, led by Lt. Col. John H. DeWitt, Jr., aimed to prove that it could indeed be penetrated. A group of radar scientists awaiting their discharge from the Army modified a radar antenna – including significantly boosting its output power – and placed it in the northeast corner of Camp Evans.
Location of the Radar Antenna on the Northeast Corner of Camp Evans Circa 1946. [photo: InfoAge website]
On the morning of January 10, 1946, with the dish pointed at the rising moon, a series of radar signals was broadcast. Exactly 2.5 seconds after each signal’s broadcast, its corresponding echo was detected. This was significant because 2.5 seconds is precisely the time required for light to travel the round trip distance between the earth and the moon. Project Diana – and her scientists – had successfully demonstrated that the ionosphere was, in fact, penetrable, and communication beyond our planet was possible. And thus was born the Space Age – as well as the field of Radar Astronomy.
SCR-271 Bedspring RADAR Antenna Pointing at the Moon [photo: David Mofenson; InfoAge website]By mid-1958 the United States had launched the Television InfraRed Observation Satellite (TIROS) program designed to study the viability of using satellite imagery and observations as a means of studying the Earth and improving weather forecasting. As part of this effort, the original “Moonbounce” antenna was replaced with a 60-foot parabolic radio antenna dish which would serve as the project’s downlink Ground Communication Station.
60-Meter Parabolic Dish Being Constructed on Project Diana Site [photo: Frank Vosk; InfoAge website]On April 1, 1960, NASA successfully launched its TIROS I satellite and the “Silent Sentinel Radio Dish” at Camp Evans began receiving its data being sent down to earth.
TIROS I Satellite [photo: NASA; National Space Science Data Center]The resulting images were so astonishing and groundbreaking that the first photos received from TIROS I were immediately printed and flown to Washington where they were presented to President Eisenhower by NASA Administrator T. Keith Glennan.
President Eisenhower and NASA Administrator Glennan Viewing the First Satellite Images from TIROS I. [photo: wikimedia commons]The TIROS program would go on to be instrumental in meteorological applications not only because it provided the first accurate weather forecasts and hurricane tracking based on satellite information, but also because it began providing continuous coverage of the earth’s weather in 1962, and ultimately lead to the development of more sophisticated observational satellites. [1]
In addition to serving as the downlink Ground Communications Center for the TIROS I and TIROS II satellites, this same dish has also tracked:
Explorer 1, America’s first satellite, in January, 1958 (pre-dates the launch of TIROS I), and
Sadly, by the mid-1970s, the technology within the TIROS dish (officially named the TLM-18 Space Telemetry Antenna) had become obsolete, and it was retired. Camp Evans was decommissioned and closed in 1993 and its land was transferred to the National Park Service. But in 2012, Camp Evans was designated a National Historic Landmark, and thus began a new, revitalized era for this immensely significant site. In addition to the TIROS Dish and the InfoAge Science History Learning Center and Museum, Camp Evans is also home to:
The Military History Museum;
The Radio Technology Museum;
The National Broadcasters’ Hall of Fame.
The Apollo Guidance Computer, Just One of the Many Historical Exhibits on Display at the InfoAge Science History Learning Center and Museum at Historic Camp Evans [photo: Robert Raia Photography]
DISH RESTORATION
In 2001, InfoAge stepped in and began preserving and restoring the mechanical systems of the TIROS dish. In 2006, a donation from Harris Corporation allowed the dish to be completely repainted and preserved.
Norman Jarosik, Senior Research Physicist at Princeton University and Daniel Marlow, PhD. and Evans Crawford 1911 Professor of Physics at Princeton, as well as countless volunteers from the University, InfoAge, Wall Township (NJ), and the Ocean-Monmouth Amateur Radio Club, Inc. (OMARC) have provided the engineering/scientific knowledge and sweat-equity required to refurbish and update the inoperative radio dish. The original vacuum-tube technology has been replaced with smaller electronic counterparts. Rusty equipment has been replaced. Seized/inoperative motors have been reconditioned and rebuilt. And system-level software controls have been added. The TIROS dish has been transformed into a truly modern, state-of-the-art Radio Astronomy Satellite Dish and Control Center.
The TIROS Dish as it Appears Today [photo: Nancy J. Graziano]On January 19, 2015, scientists from Princeton University pointed the dish skyward toward the center of our galaxy and detected a clear peak at 1420.4 MHz, the well-known 21 cm emission line originating from the deepest recesses of the Milky Way – the dish was working!
The Control Console Today. [photo: Nancy J. Graziano]
FUTURE PLANS
After almost 15 years of restoration and nearly 40 years since it last listened to the sky, the TIROS dish is once again operational, is detecting radio signals from the universe, and is well on its way to be used for science education.
Work continues on renovating Building 9162, the original TIROS Control Building, to convert it into the InfoAge Visitor Center. Plans include a NASA-style control room with theater seating for 20-30 students, a full-scale model of the original TIROS I satellite, and other exhibits dedicated to the history of Project Diana, the TIROS program, and the scientific impact these projects have had on our daily lives.
Artist’s Conception: Visitor Center Floorplan [credit: InfoAge]Future activities being planned using the dish include a Moonbounce experiment, communicating with NOAA weather satellites, performing real-time satellite imaging, viewing the Milky Way in the radio spectrum, and tracking deep space pulsars.
If you are interested in visiting the InfoAge Science History Learning Center and Museum at Historic Camp Evans, they are open to the public on Wednesdays, Saturdays, and Sundays, from 1-5pm.
To learn more about Camp Evans, Project Diana, the TIROS Satellite project, and InfoAge, tune into this week’s Weekly Space Hangout. This week’s special guest is Stephen Fowler, the Creative Director at InfoAge. He will be chatting with Fraser about the history and plans for Camp Evans and the TIROS dish.
Still want to learn more? Click on any of the links provided in this article, or visit the following sites:
"Color" radio image of galactic cluster Abell 2256. Credit: Owen et al., NRAO/AUI/NSF.
Even though it’s said that the average human eye can discern from seven to ten million different values and hues of colors, in reality our eyes are sensitive to only a very small section of the entire electromagnetic spectrum, corresponding to wavelengths in the range of 400 to 700 nanometers. Above and below those ranges lie enormously diverse segments of the EM spectrum, from minuscule yet powerful gamma rays to incredibly long, low-frequency radio waves.
Astronomers observe the Universe in all wavelengths because many objects and phenomena can only be detected in EM ranges other than visible light (which itself can easily be blocked by clouds of dense gas and dust.) But if we could see in radio waves the same way we do in visible light waves – that is with longer wavelengths being perceived as “red” and shorter wavelengths seen as “violet,” with all the blues, greens, and yellows in between – our world would look quite different… especially the night sky, which would be filled with fantastic shapes like those seen above!
View of the VLA in New Mexico. Image courtesy of NRAO/AUI.
Created from observations made at the Very Large Array in New Mexico, the image above shows a cluster of over 500 colliding galaxies located 800 million light-years away called Abell 2256. An intriguing target of study across the entire electromagnetic spectrum, here Abell 2256 (A2256 for short) has had its radio emissions mapped to the corresponding colors our eyes can see.
Within an area about the same width as the full Moon a space battle between magical cosmic creatures seems to be taking place! (In reality A2256 spans about 4 million light-years.)
See a visible-light image of A2256 by amateur astronomer Rick Johnson here.
The VLA radio observations will help researchers determine what’s happening within A2256, where multiple groups of galaxy clusters are interacting.
“The image reveals details of the interactions between the two merging clusters and suggests that previously unexpected physical processes are at work in such encounters,” said Frazer Owen of the National Radio Astronomy Observatory (NRAO).
Radio image of the night sky. (Credit: Max Planck Institute for Radio Astronomy, generated by Glyn Haslam.)
The prospect of alien invasion has sent shivers down the spines of science fiction fans ever since H. G. Wells published his classic “The War of the Worlds” in 1897. Drawing on the science of his times, Wells envisioned Mars as an arid dying world, whose inhabitants coveted the lush blue Earth. Wells’ portrayal of Martian imperialism had a political message. As an opponent of British colonialism, he wanted his countrymen to imagine what colonialism would be like from the other side. Although opponents of METI seldom explicitly invoke the spectre of alien invasion, some do view the human history of colonialism as a possible model for how aliens might treat us. The eminent physicist Stephen Hawking warned that “If aliens visit us, the outcome would be much as when Columbus landed in America, which didn’t turn our well for the Native Americans”. The illustration from Well’s novel shows a Martian fighting machine attacking the British warship HMS Thunderchild.
(credit: Henrique Alvim Correa, 1906, for the novel “The War of the Worlds”)
Should we beam messages into deep space, announcing our presence to any extraterrestrial civilizations that might be out there? Or, should we just listen? Since the beginnings of the modern Search for Extraterrestrial Intelligence (SETI), radio astronomers have, for the most part, followed the listening strategy.
In 1999, that consensus was shattered. Without consulting with other members of the community of scientists involved in SETI, a team of radio astronomers at the Evpatoria Radar Telescope in Crimea, led by Alexander Zaitsev, beamed an interstellar message called ‘Cosmic Call’ to four nearby sun-like stars. The project was funded by an American company called Team Encounter and used proceeds obtained by allowing members of the general public to submit text and images for the message in exchange for a fee.
Similar additional transmissions were made from Evpatoria in 2001, 2003, and 2008. In all, transmissions were sent towards twenty stars within less than 100 light years of the sun. The new strategy was called Messaging to Extraterrestrial Intelligence (METI). Although Zaitsev was not the first to transmit an interstellar message, he and his associates where the first to systematically broadcast to nearby stars. The 70 meter radar telescope at Evpatoria is the second largest radar telescope in the world.
In the wake of the Evpatoria transmissions a number of smaller former NASA tracking and research stations collected revenue by making METI transmissions as commercially funded publicity stunts. These included a transmission in the fictional Klingon language from Star Trek to promote the premier of an opera, a Dorito’s commercial, and the entirety of the 2008 remake of the classic science fiction movie “The Day the Earth Stood Still”. The specifications of these commercial signals have not been made public, but they were most likely much too faint to be detectable at interstellar distances with instruments comparable to those possessed by humans.
Zaitsev’s actions stirred divisive controversy among the community of scientists and scholars concerned with the field. The two sides of the debate faced off in a recent special issue of the Journal of the British Interplanetary Society, resulting from a live debate sponsored in 2010 by the Royal Society at Buckinghamshire, north of London, England.
Alexander L. Zaitsev- Chief scientist of the Russian Academy of Science’s Institute of Radio Engineering and Electronics, and head of the group that transmitted interstellar messages using the Evpatoria Planetary Radar telescope. (credit: Rumin)
Modern SETI got its start in 1959, when astrophysicists Giuseppe Cocconi and Phillip Morrison published a paper in the prestigious scientific journal Nature, in which they showed that the radio telescopes of the time were capable of receiving signals transmitted by similar counterparts at the distances of nearby stars. Just months later, radio astronomer Frank Drake turned an 85 foot radio telescope dish towards two nearby sun-like stars and conducted Project Ozma, the first SETI listening experiment. Morrison, Drake, and the young Carl Sagan supposed that extraterrestrial civilizations would “do the heavy lifting” of establishing powerful and expensive radio beacons announcing their presence. Humans, as cosmic newcomers that had just invented radio telescopes, should search and listen. There was no need to take the risk, however small, of revealing our presence to potentially hostile aliens.
Drake and Sagan did indulge in one seeming exception to their own moratorium. In 1974, the pair devised a brief 1679 bit message that was transmitted from the giant Arecibo Radar Telescope in Puerto Rico. But the transmission was not a serious attempt at interstellar messaging. By intent, it was aimed at a vastly distant star cluster 25,000 light years away. It merely served to demonstrate the new capabilities of the telescope at a rededication ceremony after a major upgrade.
In the 1980’s and 90’s SETI researchers and scholars sought to formulate a set of informal rules for the conduct of their research. The First SETI Protocol specified that any reply to a confirmed alien message must be preceded by international consultations, and an agreement on the content of the reply. It was silent on the issue of transmissions sent prior to the discovery of an extraterrestrial signal.
David Brin- Space scientist, futurist consultant, and science fiction writer (credit: Glogger)A Second SETI Protocol was to have addressed the issue, but, somewhere along the way, critics charge, something went wrong. David Brin, a space scientist, futurist consultant, and science fiction writer was a participant in the protocol discussion. He charged that “collegial discussion started falling apart” and “drastic alterations of earlier consensus agreements were rubber-stamped, with the blatant goal of removing all obstacles from the path of those pursuing METI”.
Brin accuses “the core community that clusters around the SETI Institute in Silicon Valley, California”, including astronomers Jill Tartar and Seth Shostak of “running interference for and enabling others around the world- such as Russian radio astronomer Dr. Alexander Zaitsev” to engage in METI efforts. Shostak denies this, and claims he simply sees no clear criteria for regulating such transmissions.
Brin, along with Michael A. G. Michaud, a former U.S. Foreign Service Officer and diplomat who chaired the committee that formulated the first and second protocol, and John Billingham, the former head of NASA’s short lived SETI effort, resigned their memberships in SETI related committees to protest the alterations to the second protocol.
The founders of SETI felt that extraterrestrial intelligence was likely to be benign. Carl Sagan speculated that extraterrestrial civilizations (ETCs) older than ours would, under the pressure of necessity, become peaceful and environmentally responsible, because those that didn’t would self-destruct. Extraterrestrials, they supposed, would engage in interstellar messaging because of a wish to share their knowledge and learn from others. They supposed that ETCs would establish powerful omnidirectional beacons in order to assist others in finding them and joining a communications network that might span the galaxy. Most SETI searches have been optimized for detecting such steady constantly transmitting beacons.
Over the fifty years since the beginnings of SETI, searches have been sporadic and plagued with constant funding problems. The space of possible directions, frequencies, and coding strategies has only barely been sampled so far. Still, David Brin contends that whole swaths of possibilities have been eliminated “including gaudy tutorial beacons that advanced ETCs would supposedly erect, blaring helpful insights to aid all newcomers along the rocky paths”. The absence of obvious, easily detectable evidence of extraterrestrial intelligence has led some to speak of the “Great Silence”. Something, Brin notes, “has kept the prevalence and visibility of ETCs below our threshold of observation”. If alien civilizations are being quiet, could it be that they know something that we don’t know about some danger?
Alexander Zaitsev thinks that such fears are unfounded, but that other civilizations might suffer from the same reluctance to transmit that he sees as plaguing humanity. Humanity, he thinks, should break the silence by beaming messages to its possible neighbors. He compares the current state of humanity to that of a man trapped in a one-man prison cell. “We”, he writes “do not want to live in a cocoon, in a ‘one –man cell’, without any rights to send a message outside, because such a life is not INTERESTING! Civilizations forced to hide and tremble because of farfetched fears are doomed to extinction”. He notes that in the ‘60’s astronomer Sebastian von Hoerner speculated that civilizations that don’t engage in interstellar communication eventually decline through “loss of interest”.
METI critics maintain that questions of whether or not to send powerful, targeted, narrowly beamed interstellar transmissions, and of what the content of those transmissions should be needs to be the subject of broad international and public discussion. Until such discussion has taken place, they want a temporary moratorium on such transmissions.
Seth Shostak- SETI Institute radio astronomer (credit: B D Engler)On the other hand, SETI Institute radio astronomer Seth Shostak thinks that such deliberations would be pointless. Signals already leak into space from radio and television broadcasting, and from civilian and military radar. Although these signals are too faint to be detected at interstellar distances with current human technology, Shostak contends that with the rapid growth in radio telescope technology, ETCs with technology even a few centuries in advance of ours could detect this radio leakage. Billingham and Benford counter that to collect enough energy to tune in on such leakage; an antenna with a surface area of more than 20,000 square kilometers would be needed. This is larger than the city of Chicago. If humans tried to construct such a telescope with current technology it would cost 60 trillion dollars.
Shostak argues that exotic possibilities might be available to a very technologically advanced society. If a telescope were placed at a distance of 550 times the Earth’s distance from the sun, it would be in a position to use the sun’s gravitational field as a gigantic lens. This would give it an effective collecting area vastly larger than the city of Chicago, for free. If advanced extraterrestrials made use of their star’s gravitational field in this way, Shostak maintains “that would give them the capacity to observe many varieties of terrestrial transmissions, and in the optical they would have adequate sensitivity to pick up the glow of street lamps”. Even Brin conceded that this idea was “intriguing”.
Civilizations in a position to do us potential harm through interstellar travel, Shostak contends, would necessarily be technologically advanced enough to have such capabilities. “We cannot pretend that our present level of activity with respect to broadcasting or radar usage is ‘safe’. If danger exists, we’re already vulnerable” he concludes. With no clear means to say what extraterrestrials can or can’t detect, Shostak feels the SETI community has nothing concrete to contribute to the regulation of radio transmissions.
Could extraterrestrials harm us? In 1897 H. G. Wells published his science fiction classic “The War of the Worlds” in which Earth was invaded by Martians fleeing their arid, dying world. Besides being scientifically plausible in terms of its times, Wells’ novel had a political message. An opponent of British colonialism, he wanted his countrymen to imagine what imperialism was like from the other side. Tales of alien invasion have been a staple of science fiction ever since. Some still regard European colonialism as a possible model for how extraterrestrials might treat humanity. The eminent physicist Steven Hawking thinks very advanced civilizations might have mastered interstellar travel. Hawking warned that “If aliens visit us, the outcome would be much as when Columbus landed in America, which didn’t turn out well for the Native Americans”.
Though dismissing Hawking’s fears of alien invasion as an “unlikely speculation”, David Brin notes that interstellar travel by small automated probes is quite feasible, and that such a probe could potentially do harm to us in many ways. It might, for example, steer an asteroid onto a collision course with Earth. A relatively small projectile traveling at one tenth the speed of light could wreak terrible damage by simply colliding with our planet. “The list of unlikely, but physically quite possible scenarios is very long” he warns.
Diplomat Michael Michaud warns that “We can all understand the frustration of not finding any signals after fifty years of intermittent searching” but “Impatience with the search is not a sufficient justification for introducing a new level of potential risk for our entire species”.
METI critics David Brin, James Benford, and James Billingham think that the current lack of results from SETI warrants a different sort of response than METI. They call for a reassessment of the search strategy. From the outset, SETI researchers have assumed that extraterrestrials will use steady beacons transmitting constantly in all directions to attract our attention. Recent studies of interstellar radio propagation and the economics of signaling show that such a beacon, which would need to operate on a vast timescale, is not an efficient way to signal.
Instead, an alien civilization might compile a list of potentially habitable worlds in its neighborhood and train a narrowly beamed signal on each member of the list in succession. Such brief “ping” messages might be repeated, in sequence, once a year, once a decade, or once a millennium. Benford and Billingham note that most SETI searches would miss this sort of signal.
The SETI Institute’s Allen telescope array, for example, is designed to target narrow patches of sky (such as the space around a sun-like star) and search those patches in sequence, for the presence of continuously transmitting beacons. It would miss a transient “ping” signal, because it would be unlikely to be looking in the right place at the right time. Ironically, the Evpatoria messages, transmitted for less than a day, are examples of such transient signals.
Benford and Billingham propose the construction of a new radio telescope array designed to constantly monitor the galactic plane (where stars are most abundant) for transient signals. Such a telescope array, they estimate, would cost about 12 million dollars, whereas a serious, sustained METI program would cost billions.
The METI controversy continues. On February 13, the two camps debated each other at the American Association for the Advancement of Science conference in San Jose, California. At that conference David Brin commented “It’s an area where opinion rules, and everyone has a fierce opinion”. In the wake of the meeting a group of 28 scientists, scholars, and business leaders issued a statement that “We feel the decision whether or not to transmit must be based on a worldwide consensus, and not a decision based on the wishes of a few individuals with access to powerful communications equipment”.
New images returned by the Planck telescope (right) begin to rival the complexity and beauty of a great artists imagination - Starry Night.A visulization of the Planck data represents the interaction of interstellar dust with the galactic magnetic field. Color defines the intensity of dust emisions and the measurements of polarized light reveals the direction of the magnetic field lines. (Credits: Vincent Van Gogh, ESA)
From the vantage point of a window in an insane asylum, Vincent van Gogh painted one of the most noted and valued artistic works in human history. It was the summer of 1889. With his post-impressionist paint strokes, Starry Night depicts a night sky before sunrise that undulates, flows and is never settled. Scientific discoveries are revealing a Cosmos with such characteristics.
Since Vincent’s time, artists and scientists have taken their respective paths to convey and understand the natural world. The latest released images taken by the European Planck Space Telescope reveals new exquisite details of our Universe that begin to touch upon the paint strokes of the great master and at the same time looks back nearly to the beginning of time. Since Van Gogh – the passage of 125 years – scientists have constructed a progressively intricate and incredible description of the Universe.
New images returned by the Planck telescope (right) begin to rival the complexity and beauty of a great artists imagination – Starry Night.A visulization of the Planck data represents the interaction of interstellar dust with the galactic magnetic field. Color defines the intensity of dust emisions and the measurements of polarized light reveals the direction of the magnetic field lines. (Credits: Vincent Van Gogh, ESA)
The path from Van Gogh to the Planck Telescope imagery is indirect, an abstraction akin to the impressionism of van Gogh’s era. Impressionists in the 1800s showed us that the human mind could interpret and imagine the world beyond the limitations of our five senses. Furthermore, optics since the time of Galileo had begun to extend the capability of our senses.
A photograph of James Clerk Maxwell and a self-portrait of Vincent van Gogh. Maxwell’s equations and impressionism in the fine arts in the 19th Century sparked an enhanced perception, expression and abstraction of the World and began a trek of knowledge and technology into the modern era. (Credit: National Gallery of Art, Public Domain)
Mathematics is perhaps the greatest form of abstraction of our vision of the World, the Cosmos. The path of science from the era of van Gogh began with his contemporary, James Clerk Maxwell who owes inspiration from the experimentalist Michael Faraday. The Maxwell equations mathematically define the nature of electricity and magnetism. Since Maxwell, electricity, magnetism and light have been intertwined. His equations are now a derivative of a more universal equation – the Standard Model of the Universe. The accompanying Universe Today article by Ramin Skibba describes in more detail the new findings by Planck Mission scientists and its impact on the Standard Model.
The work of Maxwell and experimentalists such as Faraday, Michelson and Morley built an overwhelming body of knowledge upon which Albert Einstein was able to write his papers of 1905, his miracle year (Annus mirabilis). His theories of the Universe have been interpreted, verified time and again and lead directly to the Universe studied by scientists employing the Planck Telescope.
The first Solvay Conference in 1911 was organized by Max Planck and Hendrik Lorentz. Planck is standing, second from left. The first Solvay, by invitation only, included most of the greatest scientists of the early 20th Century. While Planck is known for his work on quanta, the groundwork for quantum theory – the Universe in minutiae , the Planck telescope is surveying the Universe in the large. Physicists are closer to unifying the nature of the two extremes. Insets – Planck (1933, 1901).
In 1908, the German physicist Max Planck, for whom the ESA telescope is named, recognized the importance of Einstein’s work and finally invited him to Berlin and away from the obscurity of a patent office in Bern, Switzerland.
As Einstein spent a decade to complete his greatest work, the General Theory of Relativity, astronomers began to apply more powerful tools to their trade. Edwin Hubble, born in the year van Gogh painted Starry Night, began to observe the night sky with the most powerful telescope in the World, the Mt Wilson 100 inch Hooker Telescope. In the 1920s, Hubble discovered that the Milky Way was not the whole Universe but rather an island universe, one amongst billions of galaxies. His observations revealed that the Milky Way was a spiral galaxy of a form similar to neighboring galaxies, for example, M31, the Andromeda Galaxy.
Pablo Picasso and Albert Einstein were human wrecking balls in their respective professions. What began with Faraday and Maxwell, van Gogh and Gaugin were taken to new heights. We are encapsulated in the technology derived from these masters but are able to break free of the confinement technology can impose through the expression and art of Picasso and his contemporaries.
Einstein’s equations and Picasso’s abstraction created another rush of discovery and expressionism that propel us for another 50 years. Their influence continues to impact our lives today.
The Andromeda Galaxy, M31, the nearest spiral galaxy to the Milky Way, several times the angular size of the Moon. First photographed by Isaac Roberts, 1899 (inset), spirals are a function of gravity and the propagation of shock waves, across the expanses of such galaxies are electromagnetic fields such as reported by Planck mission scientists.
Telescopes of Hubble’s era reached their peak with the Palomar 200 inch telescope, four times the light gathering power of Mount Wilson’s. Astronomy had to await the development of modern electronics. Improvements in photographic techniques would pale in comparison to what was to come.
The development of electronics was accelerated by the pressures placed upon opposing forces during World War II. Karl Jansky developed radio astronomy in the 1930s which benefited from research that followed during the war years. Jansky detected the radio signature of the Milky Way. As Maxwell and others imagined, astronomy began to expand beyond just visible light – into the infrared and radio waves. Discovery of the Cosmic Microwave Background (CMB) in 1964 by Arno Penzias and Robert Wilson is arguably the greatest discovery from observations in the radio wave (and microwave) region of the electromagnetic spectrum.
From 1937 to the present day, radio astronomy has been an ever refining merger of electronics and optics. Karl Jansky’s first radio telescope, 1937 (inset) and the great ALMA array now in operation studying the Universe in the microwave region of the electromagnetic spectrum. (Credits: ESO)
Analog electronics could augment photographic studies. Vacuum tubes led to photo-multiplier tubes that could count photons and measure more accurately the dynamics of stars and the spectral imagery of planets, nebulas and whole galaxies. Then in the 1947, three physicists at Bell Labs , John Bardeen, Walter Brattain, and William Shockley created the transistor that continues to transform the World today.
For astronomy and our image of the Universe, it meant more acute imagery of the Universe and imagery spanning across the whole electromagnetic spectrum. Infrared Astronomy developed slowly beginning in the 1800s but it was solid state electronics in the 1960s when it came of age. Microwave or Millimeter Radio Astronomy required a marriage of radio astronomy and solid state electronics. The first practical millimeter wave telescope began operations in 1980 at Kitt Peak Observatory.
An early work of Picasso (center), the work at Bell Labs of John Bardeen, Walter Brattain, and William Shockley and the mobile art of Alexander Calder. As artists attempt to balance color and shape, the Bell Lab engineers balanced electrons essentially on the head of a pin, across junctions to create the first transistor.
With further improvements in solid state electronics and development of extremely accurate timing devices and development of low-temperature solid state electronics, astronomy has reached the present day. With modern rocketry, sensitive devices such as the Hubble and Planck Space Telescopes have been lofted into orbit and above the opaque atmosphere surrounding the Earth.
In 1964, the Cosmic Microwave Background (CMB) was discovered. In the early 1990s, the COBE space telescope returned even more detailed results and now Planck has refined and expanded upon IRAS, COBE and BICEP observations of the CMB. Inset, first light observations of the Planck mission. (Photo Credits: ESA)
Astronomers and physicists now probe the Universe across the whole electromagnetic spectrum generating terabytes of data and abstractions of the raw data allow us to look out into the Universe with effectively a sixth sense, that which is given to us by 21st century technology. What a remarkable coincidence that the observations of our best telescopes peering through hundreds of thousands of light years, even more so, back 13.8 billion years to the beginning of time, reveal images of the Universe that are not unlike the brilliant and beautiful paintings of a human with a mind that gave him no choice but to see the world differently.
Now 125 years later, this sixth sense forces us to see the World in a similar light. Peer up into the sky and you can imagine the planetary systems revolving around nearly every star, swirling clouds of spiral galaxies, one even larger in the sky than our Moon, and waves of magnetic fields everywhere across the starry night.
Individual radar images of 2004 BL86 and its moon. The asteroid appears very lumpy, possibly from unresolved crater rims. The moon appears elongated but that may be an artifact and not its true shape. Credit: NASA
New video of 2004 BL86 and its moon
Newly processed images of asteroid 2004 BL86 made during its brush with Earth Monday night reveal fresh details of its lumpy surface and orbiting moon. We’ve learned from both optical and radar data that Alpha, the main body, spins once every 2.6 hours. Beta (the moon) spins more slowly.
The images were made by bouncing radio waves off the surface of the bodies using NASA’s 230-foot-wide (70-meter) Deep Space Network antenna at Goldstone, Calif. Radar “pinging” reveals information about the shape, velocity, rotation rate and surface features of close-approaching asteroids. But the resulting images can be confusing to interpret. Why? Because they’re not really photos as we know it.
For one, the moon appears to be revolving perpendicular to the main body which would be very unusual. Most moons orbit their primary approximately in the plane of its equator like Earth’s moon and Jupiter’s four Galilean moons. That’s almost certainly the case with Beta. Radar imagery is assembled from echoes or radio signals returned from the asteroid after bouncing off its surface. Unlike an optical image, we see the asteroid by reflected pulses of radio energy beamed from the antenna. To interpret them, we’ll need to put on our radar glasses.
Bright areas don’t necessarily appear bright to the eye because radar sees the world differently. Metallic asteroids appear much brighter than stony types; rougher surfaces also look brighter than smooth ones. In a sense these aren’t pictures at all but graphs of the radar pulse’s time delay, Doppler shift and intensity that have been converted into an image.
Another set of images of 2004 BL86 and its moon. Credit: NAIC Observatory / Arecibo Observatory
In the images above, the left to right direction or x-axis in the photo plots the toward and away motion or Doppler shift of the asteroid. You’ll recall that light from an object approaching Earth gets bunched up into shorter wavelengths or blue-shifted compared to red-shifted light given off by an object moving away from Earth. A more rapidly rotating object will appear larger than one spinning slowly. The moon appears elongated probably because it’s rotating more slowly than the Alpha primary.
Meanwhile, the up and down direction or y-axis in the images shows the time delay in the reflected radar pulse on its return trip to the transmitter. Movement up and down indicates a change in 2004 BL86’s distance from the transmitter, and movement left to right indicates rotation. Brightness variations depend on the strength of the returned signal with more radar-reflective areas appearing brighter. The moon appears quite bright because – assuming it’s rotating more slowly – the total signal strength is concentrated in one small area compared to being spread out by the faster-spinning main body.
If that’s not enough to wrap your brain around, consider that any particular point in the image maps to multiple points on the real asteroid. That means no matter how oddly shaped 2004 BL86 is in real life, it appears round or oval in radar images. Only multiple observations over time can help us learn the true shape of the asteroid.
You’ll often notice that radar images of asteroids appear to be lighted from directly above or below. The brighter edge indicates the radar pulse is returning from the leading edge of the object, the region closest to the dish. The further down you go in the image, the farther away that part of the asteroid is from the radar and the darker it appears.
Imagine for a moment an asteroid that’s either not rotating or rotating with one of its poles pointed exactly toward Earth. In radar images it would appear as a vertical line!
If you’re curious to learn more about the nature of radar images, here are two great resources:
![Plaque Commemorating the Designation of Camp Evans as a National Historic Landmark. April 2, 2015. [photo: Robert Raia Photography]](http://www.stemmingthetide.net/wp-content/uploads/2015/06/NHL-Plaque-Rob.jpg)
![SCR-271 Bedspring RADAR Antenna Pointing at the Moon [photo: David Mofenson; InfoAge website]](http://www.stemmingthetide.net/wp-content/uploads/2015/06/d-i-030-David-Mofenson.jpg)
![60-Meter Parabolic Dish Being Constructed on Project Diana Site [photo: Frank Vosk; InfoAge website]](http://www.stemmingthetide.net/wp-content/uploads/2015/06/Dish-Assembly-1-w-Frank-Vosk.jpg)
![President Eisenhower and NASA Administrator Glennan Viewing the First Satellite Images from TIROS I. [photo: wikimedia commons]](http://www.stemmingthetide.net/wp-content/uploads/2015/06/President_Eisenhower_and_NASA_Administrator_Glennan_examine_photographs_taken_by_TIROS-1.jpg)
![The TIROS Dish as it Appears Today [photo: Nancy J. Graziano]](http://www.stemmingthetide.net/wp-content/uploads/2015/06/TIROS-Dish-Today-njg.jpg)
![The Control Console Today. [photo: Nancy J. Graziano]](http://www.stemmingthetide.net/wp-content/uploads/2015/06/Control-Console-njg.jpg)
![Visitor Center Floorplan [credit: InfoAge]](http://www.stemmingthetide.net/wp-content/uploads/2015/06/Floorplan.jpg)
