A graphic designer in Rhode Island, Jason writes about space exploration on his blog Lights In The Dark, Discovery News, and, of course, here on Universe Today. Ad astra!
Cassini image of Saturn's rings from Dec. 20, 2012 (NASA/JPL-Caltech/SSI)
As Saturn steadily moves along its 29.7-year-long orbit toward summertime in its northern hemisphere NASA’s Cassini spacecraft is along for the ride, giving astronomers a front-row seat to seasonal changes taking place on the ringed planet.
One of these fluctuations is the anticipated disappearance of the “spokes” found in the rings, a few of which can be seen above in an image captured on Dec. 20 of last year.
First identified by Voyager in 1980, spokes are ghostly streaks of varying size and brightness that stretch radially across Saturn’s ring system. They orbit around the planet with the ring particles and can last for hours before fading away.
Under the right lighting conditions spokes can appear dark, as seen in this image from Jan. 2010 (NASA/JPL/SSI)
One of the most elusive and transient of features found on Saturn, spokes are thought to be made up of larger microscopic particles of ice — each at least a micron or more — although exactly what makes them gather together isn’t yet known.
They are believed to be associated with interactions between ring particles and Saturn’s electromagnetic field.
“The spokes are most prominent at a point in the rings where the ring particles are moving at the same speed as Saturn’s electromagnetic field,” said Brad Wallis, Cassini rings discipline scientist. “That idea and variations of it are still the most prominent theories about the spokes.”
Other researchers have suggested that they may be caused by electron beams issuing outwards along magnetic field lines from lightning storms in Saturn’s atmosphere.
Regardless of how they are created, spokes are more often observed when sunlight is striking the rings edge-on — that is, during the spring and autumn equinoxes. Perhaps the increased solar radiation along Saturn’s equator increases the formation of lightning-generating storms, in turn creating more spokes? It’s only a guess, but Cassini — and astronomers — will be watching to see if these furtive features do in fact fail to appear during Saturn’s northern summer, the height of which arrives in 2016.
Enhanced-color HiRISE image of impact craters from MSL's ballast weights (NASA/JPL-Caltech)
During its “seven minutes of terror” landing on August 6, 2012, NASA’s Mars Science Laboratory dropped quite a few things down onto the Martian surface: pieces from the cruise stage, a heat shield, a parachute, the entry capsule’s backshell, a sky crane, one carefully-placed rover (obviously) and also eight tungsten masses — weights used for ballast and orientation during the descent process.
Two 75 kilogram (165 lb) blocks were released near the top of the atmosphere and six 25 kg (55 lb) weights a bit farther down, just before the deployment of the parachute. The image above, an enhanced-color image from the HiRISE camera aboard the Mars Reconnaissance Orbiter, shows the impact craters from four of these smaller tungsten masses in high resolution. This is part of a surface scan acquired on Jan. 29, 2013.
These four craters are part of a chain of six from all the 55 kg weights. See below for context:
CLICK TO PLAY – Before-and-after images of the 55 kg-mass landing sites (NASA/JPL/MSSS)
Captured by MRO’s Context Camera shortly after the rover landed, the animation above shows the impact site of all six 55 kg masses. These impacted the Martian surface about 12 km (7.5 miles) from the Curiosity rover’s landing site.
A mosaic has been assembled showing potential craters from the larger ballast blocks as well as other, smaller pieces of the cruise stage. Check it out below or download the full 50mb image here.
HiRISE images of MSL’s impact craters (NASA/JPL/University of Arizona)
Raw Cassini image captured on 26 Feb. 2013 (NASA/JPL/SSI)
Freshly delivered from Cassini’s wide-angle camera, this raw image gives us another look at Saturn’s north pole and the curious hexagon-shaped jet stream that encircles it, as well as the spiraling vortex of clouds at its center.
Back in November we got our first good look at Saturn’s north pole in years, now that Cassini’s orbit is once again taking it high over the ringplane. With spring progressing on Saturn’s northern hemisphere the upper latitudes are getting more and more sunlight — which stirs up storm activity in its atmosphere.
The bright tops of upper-level storm clouds speckle Saturn’s skies, and a large circular cyclone can be seen near the north pole, within the darker region contained by the hexagonal jet stream. This could be a long-lived storm, as it also seems to be in the images captured on November 27.
About 25,000 km (15,500 miles) across, Saturn’s hexagon is wide enough to fit nearly four Earths inside!
The Saturn hexagon as seen by Voyager 1 in 1980 (NASA)
The hexagon was originally discovered in images taken by the Voyager spacecraft in the early 1980s. It encircles Saturn at about 77 degrees north latitude and is estimated to whip around the planet at speeds of 354 km/h (220 mph.)
“Say, do you like mystery stories? Well we have one for you. The concept: relativity.”
Well look at that, it’s a new video from John D. Boswell — aka melodysheep — which goes into autotuned detail about one of the standard principles of astrophysics, Einstein’s theory of general relativity.
Featuring clips from Michio Kaku, Brian Cox, Neil deGrasse Tyson, Brian Greene and Lisa Randall, I’d say E=mc(awesome).
John has been entertaining science fans with his Symphony of Science mixes since 2009, when his first video in the series — “A Glorious Dawn” featuring Carl Sagan — was released. Now John’s videos are eagerly anticipated by fans (like me) who follow him on YouTube and on Twitter as @musicalscience.
“E = mc2… that is the engine that lights up the stars.”
(What does Einstein’s famous mass-energy equivalence equation mean? For a brief and basic explanation, check out the American Museum of Natural History’s page here.)
View of Rhode Island from the ISS, captured by Expedition 34 Commander Kevin Ford. Providence is just past the top center edge. (NASA)
It’s a wonderful thing for children to look up to their fathers, but some kids have to look a little further than others — especially when dad is in command of the International Space Station!
Around 6 p.m. EST on February 14, the ISS passed over southern New England, and for a few brief moments the Station was directly above Rhode Island, at 37 miles wide the smallest state in the US. 240 miles up and heading northeast at 17,500 mph, the ISS quickly passed out of sight for anyone watching from the ground, but it was enough time for Heidi and Anthony Ford to get a view of the place where their father Kevin Ford has been living and working since the end of October… and thanks to Brown University’s historic Ladd Observatory and astronomer Robert Horton they got to see the Station up close while talking to their dad on the phone.
“One of the things [Anthony and I] like to do is to pop outside to watch dad fly over, which you can do on occasion when the timing is just right,” Heidi said. “We were looking at the schedule to see when the flyover would be so we could go see him. I remembered that the Ladd was open to the public, so I thought I’d call over there and see if this is something we could visit the Ladd to do.”
Robert Horton, an astronomer with Brown University, was happy to meet Heidi and Anthony at the Ladd for the flyover.
Heidi and Anthony Ford’s view of the ISS (Robert Horton/Brown University)
While the Ladd’s main 12″ telescope doesn’t have the ability to track fast-moving objects like the ISS, Horton had some at home that could. So he set one of them up at the observatory and prepared to track the station during its six-minute pass.
Just before the flyby, Heidi’s phone rang — it was her dad calling from the ISS.
“He told her, ‘I’m over Texas. I’ll be there in a few minutes,’” Horton said later in an interview with Brown reporters. “Sure enough the point of light appeared in the sky and we started to track it. They could look through the eyepiece and actually make out the solar panels while they were talking with him.”
The Brown University-run Ladd Observatory holds free public viewing nights every Tuesday, weather permitting. People line up inside the 122-year-old dome to peer through its recently restored 12″ refracting telescope at objects like the Moon, Jupiter, and Saturn, and local amateur astronomers set up their own ‘scopes on the observatory’s rooftop deck for additional viewing opportunities.
Heidi had told their dad that they’d be watching from Providence as he passed over, and luckily his schedule allowed him to make a phone call during that particular evening’s pass.
NASA astronauts Kevin Ford (foreground) and Tom Marshburn working with the Combustion Integrated Rack (CIR) Multi-user Droplet Combustion Apparatus (MDCA) in the ISS’ Destiny laboratory on Jan. 9 (NASA)
While they had both watched flyovers before, it was the first time either of them had ever seen the ISS through a telescope.
It made for a “very special Valentine’s Day,” Heidi said.
And as for Horton, who had donated the use of his telescope? He got a chance to talk with Commander Ford as well — an experience he’ll likely never forget.
“I can think of a thousand questions to ask him now that I’m not on the phone with him,” Horton said. “But, frankly, I was awestruck at the time.”
Concept art for a New Horizons postage stamp. Image Credit: Dan Durda/Southwest Research Institute
A little over a year ago Alan Stern, principal investigator on the New Horizons mission, announced the team’s plans to have a Forever Stamp issued by the US Postal Service commemorating the New Horizons spacecraft along with its targets, Pluto and Charon. Thousands signed the petition, and today the team announced a long-awaited update to all of its supporters: it’s definitely a maybe!
In an email sent out to petition signers as well as on its Facebook page, the New Horizons team noted that the stamp — conceptualized by planetary scientist and artist Dan Durda — has cleared its first major hurdle in the USPS approval process and will be submitted for review and consideration before their Advisory Committee.
Pending that approval, it will then be put on the agenda for the meeting of the Citizens’ Stamp Advisory Committee.
After that point, since no notification is made to the applicant about a stamp’s approval by the Postmaster General until a public announcement is issued it’s likely that we won’t know if there will actually be a New Horizons stamp until the spacecraft is on final approach to Pluto in July 2015. Hopefully the USPS will see the benefit to having a stamp actually ready for purchase by that time and plan accordingly, but one never knows. Until then, cross your fingers and keep an eye out for a Forever Stamp featuring the “First Spacecraft to Explore Pluto!”
“This is a chance for us all to celebrate what American space exploration can achieve though hard work, technical excellence, the spirit of scientific inquiry, and the uniquely human drive to explore.”
– Alan Stern, New Horizons Principal Investigator
USPS Forever Stamps can be used to mail a one-ounce letter regardless of when the stamps are purchased or used and no matter how prices may change in the future. Forever Stamps are always sold at the same price as a regular First-Class Mail stamp. Forever Stamps can be used for international mail, but since all international prices are higher than domestic US prices, additional postage is necessary.
These may soon be the names of Pluto's family of moons (Hubble image: NASA, ESA and M. Showalter/SETI)
The votes have been tallied and the results are in from the SETI Institute’s Pluto Rocks Poll: “Vulcan” and “Cerberus” have come out on top for names for Pluto’s most recently-discovered moons, P4 and P5.
After 450,324 votes cast over the past two weeks, Vulcan is the clear winner with a landslide 174,062 votes… due in no small part to a little Twitter intervention by Mr. William Shatner, I’m sure.
During a Google+ Hangout today, SETI Institute senior scientist Mark Showalter — who discovered the moons and opened up the poll — talked with SETI astronomer Franck Marchis and MSNBC’s Alan Boyle about the voting results. Showalter admitted that he wasn’t quite sure how well the whole internet poll thing would work out, but he’s pleased with the results.
“I had no idea what to expect,” said Showalter. “As we all know the internet can be an unruly place… but by and large this process has gone very smoothly. I feel the results are fair.”
As far as having a name from the Star Trek universe be used for an actual astronomical object?
“Vulcan works,” Showalter said. “He’s got a family tie to the whole story. Pluto and Zeus were brothers, and Vulcan is a son of Pluto.”
The other winning name, Cerberus, is currently used for an asteroid. So because the IAU typically tries to avoid confusion with two objects sharing the same exact name, Showalter said he will use the Greek version of the spelling: Kerberos.
Cerberus (or Kerberos) is the name of the giant three-headed dog that guards the gates to the underworld in Greek mythology.
Now that the international public has spoken, the next step will be to submit these names to the International Astronomical Union for official approval, a process that could take 1–2 months.
(Although who knows… maybe Bill can help move that process along as well?)
Read more about the names on the Pluto Rocks ballot here, and watch the full recorded Google+ Hangout below:
A young star is spotted firing jets of material out into space (ESA/Hubble & NASA. Acknowledgement: Gilles Chapdelaine)
Like very young humans, very young stars also tend to make a big mess out of the stuff around them — except in the case of stars it’s not crayon on the walls and Legos on the floor (ouch!) but rather huge blasts of superheated material that are launched from their poles far out into space.
The image above, acquired by the Hubble Space Telescope, shows one of these young stars caught in the act.
HL Tau is a relatively newborn star, formed “only” within the past several hundred thousand years. During that time it has scooped up vast amounts of gas and dust from the area around itself, forming a disc of hot, accelerated material that surrounds it. While most of this material eventually falls into the star, increasing its mass, some of it gets caught up in the star’s complex, rotating magnetic fields and is thrown out into space as high-speed jets.
As these jets plow thorough surrounding interstellar space they ram into nearby clouds of molecular gas, ionizing the material within them and causing them to glow brightly. These “shocks” are known as Herbig-Haro objects, after researchers George Herbig and Guillermo Haro who each discovered them independently in the early 1950s.
Detail of HH 151’s jet
In this Hubble image HH 151 is visible as a multiple-lobed cone of material fired away from HL Tau, with the leftover glows from previous outbursts dimly illuminating the rest of the scene.
The material within these jets can reach speeds of several hundred to a thousand kilometers a second. They can last anywhere from a few years to a few thousand years.
HH 151 is embedded within the larger star-forming region LDN 1551, located about 450 light-years away in the constellation Taurus. LDN 1551 is a stellar nursery full of dust, dark nebulae, newborn stars… and Herbig-Haro objects like HH 151.
(Hey, if baby stars are going to make a mess at least they can do it in the nursery.)
Color map of Mercury's varied surface. The 1,550-km-wide Caloris Basin can be seen at upper right.
Created by the MESSENGER mission team at the Johns Hopkins University Applied Physics Laboratory and the Carnegie Institution of Washington, this animation gives us a look at the spinning globe of Mercury, its surface color-coded to reflect variations in surface material reflectance.
Thousands of Wide Angle Camera images of Mercury’s surface were stitched together to create the full-planet views.
While the vibrant colors don’t accurately portray Mercury as our eyes would see it, they are valuable to scientists as they highlight the many different types of materials that make up the planet’s surface. Young crater rays surrounding fresh impact craters appear light blue or white. Medium- and dark-blue “low-reflectance material” (LRM) areas are thought to be rich in a dark, opaque mineral. Tan areas are plains formed by eruption of highly fluid lavas. Small orange spots are materials deposited by explosive volcanic eruptions.
At this point, over 99% of the Solar System’s innermost planet has been mapped by MESSENGER. Read more about the ongoing mission here.
Image/video credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
Asteroid DA14 seen from the 2.1 Kitt Peak telescope as it departed the vicinity of Earth. Credit: NOAO/Nicholas Moskovitz (MIT)
Just as anticipated, on Friday, Feb. 15, asteroid 2012 DA14 passed us by, zipping 27,000 kilometers (17,000 miles) above Earth’s surface — well within the ring of geostationary weather and communications satellites that ring our world. Traveling a breakneck 28,100 km/hr (that’s nearly five miles a second!) the 50-meter space rock was a fast-moving target for professional and amateur observers alike. And even as it was heading away from Earth DA14 was captured on camera by a team led by MIT researcher Dr. Nicholas Moskovitz using the 2.1-meter telescope at the Kitt Peak National Observatory in Tucson, AZ. The team’s images are shown above as an animated gif (you may need to click the image to play it.)
This object’s close pass, coupled with the completely unexpected appearance of a remarkably large meteor in the skies over Chelyabinsk, Russia on the morning of the same day, highlight the need for continued research of near-Earth objects (NEOs) — since there are plenty more out there where these came from.
“Flybys like this, particularly for objects smaller than 2012 DA14, are not uncommon. This one was special because we knew about it well in advance so that observations could be planned to look at how asteroids are effected by the Earth’s gravity when they come so close.”
– Dr. Nicholas Moskovitz, MIT
The animation shows 2012 DA14 passing inside the Little Dipper, crossing an area about a third the size of the full Moon in 45 minutes. North is to the left.
(For a high-resolution version of the animation, click here.)
Exterior of the 2.1-meter telescope of the Kitt Peak National Observatory (NOAO/AURA/NSF)
According to the National Optical Astronomy Observatory, which operates the Kitt Peak Observatory, Dr. Moskovitz’ NSF-supported team “are analyzing their data to measure any changes in the rotation rate of the asteroid after its close encounter with the Earth. Although asteroids are generally too small to resolve with optical telescopes, their irregular shape causes their brightness to change as they rotate. Measuring the rotation rate of the asteroid in this way allows the team to test models that predict how the earth’s gravity can affect close-passing asteroids. This will lead to a better understanding of whether objects like 2012 DA14 are rubble piles or single solid rocks.
“This is critical to understanding the potential hazards that other asteroids could pose if they collide with the Earth.”
So just how close was DA14’s “close pass?” Well, if Earth were just a few minutes farther along in its orbit, we would likely be looking at images of its impact rather than its departure.*
Although this particular asteroid isn’t expected to approach Earth so closely at any time in the foreseeable future — at least within the next 130 years — there are lots of such Earth-crossing objects within the inner Solar System… some we’re aware of, but many that we’re not. Identifying them and knowing as many details as possible about their orbits, shapes, and compositions is key.
Even this soon after the Feb. 15 flyby observations of 2012 DA14 have provided more information on its orbit and characteristics., allowing for fine-tuning of the data on it.
According to the Goldstone Radar Observatory web page, the details on 2012 DA14 are as follows:
Semimajor axis 1.002 AU
Eccentricity 0.108
Inclination 10.4 deg
Perihelion distance 0.893 AU
Aphelion distance 1.110 AU
Absolute magnitude (H) 24.4
Diameter ~50 meters (+- a factor of two)
Rotation period ~6 h (N. Moskovitz, pers. comm.)
Pole direction unknown
Lightcurve amplitude ~1 mag (N. Moskovitz, pers. comm.)
Spectral class Ld (N. Moskovitz, pers. comm.)
Goldstone is currently conducting radar observations on the asteroid. A radar map of its surface and motion is anticipated in the near future.
A bright daytime meteor witnessed over Russia on Feb. 15, 2013 (RussiaToday)
Also, in an encouraging move by international leaders in the field, during the fiftieth session of the Scientific and Technical Subcommittee of the Committee on the Peaceful Uses of Outer Space, currently being held from at the United Nation Office in Vienna, near-Earth objects are on the agenda with a final report to be issued by an Action Team. Read the report PDF here.
*According to astronomer Phil Plait, while the orbits of Earth and DA14 might intersect at some point, on the 15th of February 2013 the asteroid slipped just outside of Earth’s orbit — a little over 17,000 miles shy. “It was traveling one way and the Earth another, so they could not have hit each other on this pass no matter where Earth was in its orbit,” he wrote in an email. Still, 17,000 miles is a very close call astronomically, and according to Neil deGrasse Tyson on Twitter, it “will one day hit us, like the one in Russian [sic] last night.” When? We don’t know yet. That’s why we must keep watching.
