Set your alarm clocks for an early treat about a half an hour before sunrise on Thursday April 28 through Sunday, May 1, 2011, as there will be a planetary delight in store! Go out and with either a pair of binoculars, a small telescope, or just use your naked eyes and find an unobscured view of the Eastern horizon to see a conjunction (objects near each other in the sky) of the planets Jupiter, Mars, Venus and Mercury, below and to the left of the thin crescent moon.
Bright Venus will be easy to spot first, then Mercury followed by Jupiter. The real challenge is to find Mars which will be very close to Jupiter. See the above diagram for help on where each object is located.
If you are unlucky on the first morning, try again the following day for a chance to see this rare planetary occurrence.
While observing this close to the Sun take care and never look at the sun directly with your eyes and never through an optical instrument, as this will permanently damage your eyesight or blind you!
Only special purpose made solar telescopes and filters are safe for viewing the sun.
The Juno spacecraft passes in front of Jupiter in this artist's depiction. Juno, the second mission in NASA's New Frontiers program, will improve our understanding of the solar system by advancing studies of the origin and evolution of Jupiter. The spacecraft will carry eight instruments to investigate the existence of a solid planetary core, map Jupiter's intense magnetic field, measure the amount of water and ammonia in the deep atmosphere, and observe the planet's auroras. Credit: NASA/JPL-Caltech
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Juno, NASA’s next big mission bound for the outer planets, has arrived at the Kennedy Space Center to kick off the final leg of launch preparations in anticipation of blastoff for Jupiter this summer.
The huge solar-powered Juno spacecraft will skim to within 4800 kilometers (3000 miles) of the cloud tops of Jupiter to study the origin and evolution of our solar system’s largest planet. Understanding the mechanism of how Jupiter formed will lead to a better understanding of the origin of planetary systems around other stars throughout our galaxy.
Juno will be spinning like a windmill as it fly’s in a highly elliptical polar orbit and investigates the gas giant’s origins, structure, atmosphere and magnetosphere with a suite of nine science instruments.
Technicians at Astrotech's payload processing facility in Titusville, Fla. secure NASA's Juno spacecraft to the rotation stand for testing. The solar-powered spacecraft will orbit Jupiter's poles 33 times to find out more about the gas giant's origins. Credit: NASA/Jack Pfaller
During the five year cruise to Jupiter, the 3,600 kilogram probe will fly by Earth once in 2013 to pick up speed and accelerate Juno past the asteroid belt on its long journey to the Jovian system where it arrives in July 2016.
Juno will orbit Jupiter 33 times and search for the existence of a solid planetary core, map Jupiter’s intense magnetic field, measure the amount of water and ammonia in the deep atmosphere, and observe the planet’s auroras.
The mission will provide the first detailed glimpse of Jupiter’s poles and is set to last approximately one year. The elliptical orbit will allow Juno to avoid most of Jupiter’s harsh radiation regions that can severely damage the spacecraft systems.
Juno was designed and built by Lockheed Martin Space Systems, Denver, and air shipped in a protective shipping container inside the belly of a U.S. Air Force C-17 Globemaster cargo jet to the Astrotech payload processing facility in Titusville, Fla.
Juno undergoes acoustics testing at Lockheed Martin in Denver where the spacecraft was built. Credit: NASA/JPL-Caltech/Lockheed Martin
This week the spacecraft begins about four months of final functional testing and integration inside the climate controlled clean room and undergoes a thorough verification that all its systems are healthy. Other processing work before launch includes attachment of the long magnetometer boom and solar arrays which arrived earlier.
Juno is the first solar powered probe to be launched to the outer planets and operate at such a great distance from the sun. Since Jupiter receives 25 times less sunlight than Earth, Juno will carry three giant solar panels, each spanning more than 20 meters (66 feet) in length. They will remain continuously in sunlight from the time they are unfurled after launch through the end of the mission.
“The Juno spacecraft and the team have come a long way since this project was first conceived in 2003,” said Scott Bolton, Juno’s principal investigator, based at Southwest Research Institute in San Antonio, in a statement. “We’re only a few months away from a mission of discovery that could very well rewrite the books on not only how Jupiter was born, but how our solar system came into being.”
Juno is slated to launch aboard the most powerful version of the Atlas V rocket – augmented by 5 solid rocket boosters – from Cape Canaveral, Fla. on August 5. The launch window extends through August 26. Juno is the second mission in NASA’s New Frontiers program.
NASA’s Mars Curiosity Rover will follow Juno to the Atlas launch pad, and is scheduled to liftoff in late November 2011. Read my stories about Curiosity here and here.
Because of cuts to NASA’s budget by politicians in Washington, the long hoped for mission to investigate the Jovian moon Europa may be axed, along with other high priority science missions. Europa may harbor subsurface oceans of liquid water and is a prime target in NASA’s search for life beyond Earth.
Technicians inside the clean room at Astrotech in Titusville, Fla. guide NASA's Juno spacecraft, as it is lowered by overhead crane, onto the rotation stand for testing. Credit: NASA/Jack PfallerTechnicians at Astrotech unfurl solar array No. 1 with a magnetometer boom that will help power NASA's Juno spacecraft on a mission to Jupiter. Credit: NASAJuno's interplanetary trajectory to Jupiter. Juno will launch in August 2011 and fly by Earth once in October 2013 during its 5 year cruise to Jupiter. Click to enlarge. Credit: NASA/JPL
Saturn, imaged by Cassini on approach. Credit: CICLOPS
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Planetary rings are more than just astronomical marvels — they’re also a sort of archive, chronicling histories of impacts for decades.
A pair of studies were published online in Science today by two different teams that noticed odd characteristics in the rings of Saturn and Jupiter — and followed them to this promising conclusion. In the first, lead author Mark Showalter of the SETI Institute in Mountain View, Calif. and his team analyzed images of Jupiter’s rings observed in 1996 and 2000 by Galileo, and again in 2007 by Horizon, zeroing in on a pattern they labeled “corrugated,” like a tin roof. Around the same time, Matthew Hedman, from Cornell University in Ithaca, NY and his colleagues discovered similar ripple patterns in the rings of Saturn, from images taken by the Cassini spacecraft.
Image courtesy of Science/AAAS
The images above show how a vertical corrugation can be produced from an initially inclined ring. The top image shows a simple inclined ring (the central planet is omitted for clarity), while the lower two images show the same ring at two later times, where the ring particles’ wobbling orbits have sheared this inclined sheet into an increasingly tightly-wound spiral corrugation.
Carolyn Porco, a co-author on the Hedman-led study and director of the Cassini Imaging Central Laboratory for Operatons (CICLOPS), wrote in an email accompanying the release of the studies that “it has been known for some time that the solar system is filled with debris: small rocky bits in the inner solar system and icy bits in the
outer solar system that routinely rain down on the planets and their rings and moons. A couple hundred tons of such debris hits the Earth alone every day. Well, the origins of the spiral ripples in both ring systems have now been pinpointed to very recent impacts between clouds of cometary fragments and the rings.”
Showalter’s team describes a pair of superimposed ripple patterns that showed up in Galileo images in 1996 and again in 2000.
“These patterns behave as two independent spirals, each winding up at a rate defined by Jupiter’s gravity field,” they write. “The dominant pattern originated between July and October 1994, when the entire ring was tilted by ~2 km. We associate this with the ShoemakerLevy 9 impacts of July 1994. New Horizons images still show this pattern 13 years later and suggest that subsequent events may also have tilted the ring.”
Corrugation in Saturn's D-ring. Credit: NASA
Hedman and his team note that rippling had previously been observed in Saturn’s D ring; NASA released the above graphic to explain the phenomenon in 2006. “The C-ring corrugation seems to have been similarly generated, and indeed it was probably created by the same ring-tilting event that produced the D-ring’s corrugation,” they write.
That paper also compares the rate of impacts likely to visit each planet: “… Saturn should encounter debris clouds derived from comets disrupted by previous planetary encounters at a rate that is roughly 0.2 percent of Jupiter’s impact rate.”
They reason that if Jupiter sees impacts from 1-km-wide objects as often as once a decade, “the clouds of orbiting debris created by the disruption of a 1-km-wide comet should rain down on Saturn’s rings once every 5,000-10,000 years. The probability that debris from a previously disrupted comet would hit Saturn’s rings in the last 30 years would then be between roughly 1 percent and 0.1 percent, which is not very small. Such scenarios therefore provide a reasonable explanation for the origin of the observed corrugation in Saturn’s C ring.”
Taken together, the papers show that Saturn’s ring ripples were likely generated by a comet collision in 1983, while Jupiter’s ring ripples occurred after the impact of a comet the summer of 1994 — specifically, the impact of Comet Shoemaker-Levy 9 that left scars on Jupiter still visible today.
Showalter and his coauthors point out that impacts by comets and/or their dust clouds are common occurrences in planetary rings.
“On at least three occasions over the last few decades, these collisions have carried sufficient momentum to tilt a ring of Jupiter or Saturn off its axis by an observable distance. Once such a tilt is established, it can persist for decades, with the passage of time recorded in its ever-tightening spiral,” they write. “Within these subtle patterns, planetary rings chronicle their own battered histories.”
Both papers appear today at the Science Express website. See also the CICLOPS site.
[/caption]According to today’s Sky & Telescope press release, two bright planets will shine close together low in the western twilight from Sunday to Wednesday, March 13th to 16th. Anyone can see them with the naked eye. You’ll just need a clear sky and an open view toward the west roughly 40 minutes after sunset, as twilight fades.
Jupiter is the brighter of the two. “Mercury is pretty hard to spot most of the time, so a lot of people have never recognized it in their lives,” says Alan MacRobert, a senior editor of Sky & Telescope magazine. “With Jupiter guiding the way, now’s your chance.”
Jupiter has dominated the evening sky for several months, but now it’s on its way down and out for the season. It’ll be gone in another couple of weeks. Mercury, on the other hand, will climb a little higher in the western twilight by late March. (This refers to viewers in the world’s mid-northern latitudes, including the United States, Canada, southern Europe, and elsewhere between about 30° and 50° north latitude.)
The graphic here shows where to look.
Find a spot with a clear, open view low to the west, and you can watch Mercury passing Jupiter in twilight from March 13 to 16, 2011. Credit: Sky & Telescope magazine
The two planets will appear closest together on Monday and Tuesday, March 14 and 15, when they’ll be only about 2° apart — about the width of your thumb held at arm’s length.
Although the two planets appear close together, they’re not. Jupiter is more than 5 times farther away, at a distance of 550 million miles compared to Mercury’s 102 million miles. That means the light we see from them takes 49 and 9 minutes, respectively, to reach us.
“Don’t miss this chance to do a little astronomy from your backyard, balcony, or rooftop,” says Sky & Telescope associate editor Tony Flanders. “It’s a big universe, and planets await.”
For more skywatching information and astronomy news, visit SkyandTelescope.com or pick up Sky & Telescope, the essential magazine of astronomy since 1941.
As we know, Jupiter’s Southern Equatorial Belt has been missing beneath its icy clouds for almost a year now. While astronomers are able to use instruments like Keck – complete with infrared and adaptive optics – we here on Earth have to take our views of Jupiter a little more naturally.
As you can see from this webcam image given to us by John Chumack, even our thin earthly clouds can’t quite hide bright Jupiter. It has returned to the same ruddy, lined face that most of us fell in love with the first time we observed it. Stunning details? No… Because this is how Jupiter really looks when you first glimpse it in the eyepiece.
Right now the westering Jupiter isn’t in the best of positions for extended observing, but it is at a comfortable height and a comfortable time. While it might be tempting to throw a huge amount of magnification its way, it actually makes the view worse rather than improving it. With steady seeing condtions, around 150-200X is ideal – reducing the magnification even lower if the atmosphere is turbulent. You’ll find you’ll also have greater success using your orthoscopic or plossl design eyepieces, too. Got color filters? Go ahead and experiment! Blues, reds and yellows all cause contrast change which can reveal subtle details. As unusual as it may sound, sketching also helps. You don’t need to be a Rembrandt. Just the act of translating what the eye sees onto paper greatly improves your “human” focus.
Don’t forget the galiean moons! As you can see, Europa can look like a world of its own. While larger aperture instruments are able to resolve events like shadow transits, don’t feel left out if you have a small telescope. It’s very exciting to witness one of Jupiter’s satellites being eclipsed by the parent planet – or disappearing as it passes in front. There are even times when the moons eclipse each other! Go on… Take advantage of the early evening hours and enjoy Jupiter.
Because you never know when the perfect moment seeing will arrive…
Many thanks to John Chumack of Galactic Images for sharing his recent image of Jupiter with us.
MESSENGER's new solar system portrait, from the inside out
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Say cheese! The MESSENGER spacecraft has captured the first portrait of our Solar System from the inside looking out. The images, captured Nov. 3 and 16, 2010, were snapped with the Wide Angle Camera (WAC) and Narrow Angle Camera (NAC) of MESSENGER’s Mercury Dual Imaging System (MDIS).
All of the planets are visible except for Uranus and Neptune, which at distances of 3.0 and 4.4 billion kilometers were too faint to detect with even the longest camera exposure time of 10 seconds. Their positions are indicated. The dwarf-planet Pluto, smaller and farther away, would have been even more difficult to observe.
Earth’s Moon and Jupiter’s Galilean satellites (Callisto, Ganymede, Europa, and Io) can be seen in the NAC image insets. Our Solar System’s perch on a spiral arm provided a beautiful view of part of the Milky Way galaxy, bottom center.
The following is a graphic showing the positions of the planets when the graphic was acquired:
The new mosaic provides a complement to the Solar System portrait – that one from the outside looking in – taken by Voyager 1 in 1990.
These six narrow-angle color images were made from the first ever 'portrait' of the solar system taken by Voyager 1, which was more than 4 billion miles from Earth and about 32 degrees above the ecliptic. The spacecraft acquired a total of 60 frames for a mosaic of the solar system which shows six of the planets. Mercury is too close to the sun to be seen. Mars was not detectable by the Voyager cameras due to scattered sunlight in the optics, and Pluto was not included in the mosaic because of its small size and distance from the sun. These blown-up images, left to right and top to bottom are Venus, Earth, Jupiter, and Saturn, Uranus, Neptune. The background features in the images are artifacts resulting from the magnification. The images were taken through three color filters -- violet, blue and green -- and recombined to produce the color images. Jupiter and Saturn were resolved by the camera but Uranus and Neptune appear larger than they really are because of image smear due to spacecraft motion during the long (15 second) exposure times. Earth appears to be in a band of light because it coincidentally lies right in the center of the scattered light rays resulting from taking the image so close to the sun. Earth was a crescent only 0.12 pixels in size. Venus was 0.11 pixel in diameter. The planetary images were taken with the narrow-angle camera (1500 mm focal length). Credit: NASA/JPL
“Obtaining this portrait was a terrific feat by the MESSENGER team,” says Sean Solomon, MESSENGER principal investigator and a researcher at the Carnegie Institution. “This snapshot of our neighborhood also reminds us that Earth is a member of a planetary family that was formed by common processes four and a half billion years ago. Our spacecraft is soon to orbit the innermost member of the family, one that holds many new answers to how Earth-like planets are assembled and evolve.”
This image is a composite of three color images taken on Nov. 18, 2010, by the Gemini North telescope in Hawaii. The composite image shows a belt that had previously vanished in Jupiter's atmosphere is now reappearing. Image credit: NASA/JPL/UH/NIRI/Gemin
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Earlier this year, one of Jupiter’s stripes went missing. The Southern Equatorial Band started to get lighter and paler, and eventually disappeared. Now, follow-up images from both professional and amateur astronomers are showing some activity in the area of the SEB, and scientists now believe the vanished dark stripe is making a comeback. They say these new observations will help our understanding of the interaction between Jupiter’s winds and cloud chemistry.
“The reason Jupiter seemed to ‘lose’ this band – camouflaging itself among the surrounding white bands – is that the usual downwelling winds that are dry and keep the region clear of clouds died down,” said Glenn Orton, a research scientist at JPL. “One of the things we were looking for in the infrared was evidence that the darker material emerging to the west of the bright spot was actually the start of clearing in the cloud deck, and that is precisely what we saw.”
This image of Jupiter is a composite of three color images taken on Nov. 16, 2010, by NASA's Infrared Telescope Facility. The particles lofted by the initial outbreak are easily identified in green as high altitude particles at the upper right, with a second outbreak to the lower left. Image credit: NASA/JPL-Caltech/IRTF
This white cloud deck is made up of white ammonia ice. When the white clouds float at a higher altitude, they obscure the missing brown material, which floats at a lower altitude. Every few decades or so, the South Equatorial Belt turns completely white for perhaps one to three years, an event that has puzzled scientists for decades. This extreme change in appearance has only been seen with the South Equatorial Belt, making it unique to Jupiter and the entire solar system.
The white band wasn’t the only change on the big, gaseous planet. At the same time, Jupiter’s Great Red Spot became a darker red color. Orton said the color of the spot – a giant storm on Jupiter that is three times the size of Earth and a century or more old – will likely brighten a bit again as the South Equatorial Belt makes its comeback.
A false-color composite image of Jupiter and its South Equatorial Belt shows an unusually bright spot, or outbreak, where winds are lofting particles to high altitudes in this image made from data obtained by the W.M. Keck telescope on Nov. 11, 2010. Image credit: NASA/JPL-Caltech/W. M. Keck Observatory
The South Equatorial Belt underwent a slight brightening, known as a “fade,” just as NASA’s New Horizons spacecraft was flying by on its way to Pluto in 2007. Then there was a rapid “revival” of its usual dark color three to four months later. The last full fade and revival was a double-header event, starting with a fade in 1989, revival in 1990, then another fade and revival in 1993. Similar fades and revivals have been captured visually and photographically back to the early 20th century, and they are likely to be a long-term phenomenon in Jupiter’s atmosphere.
Scientists are particularly interested in observing this latest event because it’s the first time they’ve been able to use modern instruments to determine the details of the chemical and dynamical changes of this phenomenon. Observing this event carefully may help to refine the scientific questions to be posed by NASA’s Juno spacecraft, due to arrive at Jupiter in 2016, and a larger, proposed mission to orbit Jupiter and explore its satellite Europa after 2020.
Observations by amateur astronomers Christopher Go of Cebu City, Philippines and Anthony Wesley of Australia have helped, and scientists have used the “big guns” in Hawaii — NASA’s Infrared Telescope Facility, the W.M. Keck Observatory and the Gemini Observatory telescope.
Go imaged an outburst that piqued the interest of other astronomers. “I was fortunate to catch the outburst,” said Christopher Go, referring to the first signs that the band was coming back. “I had a meeting that evening and it went late. I caught the outburst just in time as it was rising. Had I imaged earlier, I would not have caught it,” he said.
Look! Up in the sky! Is it a bird? Is it a plane? No… It’s super Jupiter! “Jupiter is always bright, but if you think it looks a little brighter than usual this month, you’re right,” says Robert Naeye, editor in chief of Sky & Telescope magazine. “Jupiter is making its closest pass by Earth for the year. And this year’s pass is a little closer than any other between 1963 and 2022.”
Where do you find Jupiter? Try about 368 million miles away and (for most observers) low to the southeast after the skies get dark. The giant planet will reach its nearest point to us on the evening of September 20, 2010 – but will remain one of the brightest objects in the night through the end of the month.
Why does Jupiter appear to be more luminous now than at any other time? Although the varying distances over the years may seem marginal – about 10 to 11 million miles over a period of around 60 years – it translates into significance when it comes to magnitude factors. At its brightest, Jupiter can reach –2.94, and dimmest at -1.6. Just a 1% distance change can mean either 4% brighter or dimmer!
The mighty Jove has also undergone some cosmetic changes in the past year as well, making it an additional 4% brighter than usual.
For nearly a year the giant planet’s South Equatorial Belt has slowly been covered by a highly reflective ammonia cloud. Normally the SEB appears to be brown, a result of Jupiter’s chemical compounds reacting to the Sun’s ultraviolet light. Known as “chromophores”, these chemicals are known to mix with lower cloud decks and just a few stormy days could mean rising convection cells are forming crystallized ammonia – masking the light absorbing dark zone and adding to reflectivity.
Of course, a close pass doesn’t mean Jupiter is going to appear to be the size of the Moon – nor be as bright – but it’s certainly going to make a grand appearance on the nights of September 22 and September 23 when it joins Selene on the celestial scene!
But that’s not all that’s happening here. According the Sky & Telescope Magazine: Jupiter and Uranus find themselves close to the point on the sky known as the vernal equinox, where the Sun crosses the celestial equator on the first day of spring. (“Spring” here means spring in the Northern Hemisphere.) And, all of this takes place around the date when fall begins in the
Northern Hemisphere: on September 22nd. (Fall begins at 11:09 p.m. Eastern Daylight Time on that date.)
What do all these coincidences mean? “Nothing at all,” says Alan MacRobert, a senior editor at Sky & Telescope. “People forget that lots of things are going on in the sky all the time. Any particular arrangement might not happen again for centuries, but like the saying goes, there’s always something. Enjoy the show.”
Color image of impact on Jupiter on June 3, 2010. Credit: Anthony Wesley
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Poor Jupiter just can’t seem to catch a break. Ever since 1994, when our largest planet was hit by Comet Shoemaker-Levy, detections of impacts on Jupiter have occurred with increasing regularity. Most recently, an impact was witnessed on August 20. On June 3rd of 2010, (coincidentally the same day pictures from Hubble were released from a 2009 impact) Jupiter was hit yet again. Shortly after the June 3rd impact, several other telescopes joined the observing.
The June 3rd impact was novel in several respects. It was the first unexpected impact that was reported from two independent locations simultaneously. Both discoverers were observing Jupiter with aims of engaging in a bit of astrophotography. Their cameras were both set to take a series of quick images, each lasting a fifth to a tenth of a second. This short time duration is the first time astronomers have had the ability to recreate the light curve for the meteor. Additionally, both observers were using different filters (one red and one blue) allowing for exploration of the color distribution.
Analysis of the light curve revealed that the flash lasted nearly two seconds and was not symmetric; The decay in brightness occurred faster than the increase at onset. Additionally, the curve showed several distinct “bumps” which indicated a flickering that is commonly seen on meteors on Earth.
The light released in the burning up of the object was used to estimate the total energy-released and in turn the mass of the object. The total energy released was estimated to be between roughly (1.0–4.0) × 1015 Joules (or 250–1000 kilotons).
Follow-up observations from Hubble three days later revealed no scars from the impact. In the July 2009 impact, a hole punched in the clouds remained for several days. This indicated the object in the June 3 impact was considerably smaller and burned up before it was able to reach the visible cloud decks.
Observations intended to find debris came up empty. Infrared observations showed that no thermal signature was left even as little as 18 hours following the discovery.
Assuming that the object was an asteroid with a relative speed of ~60 km/sec and a density of ~2 g/cm3, the team estimated the size of the object to be between 8 and 13 meters, similar to the size of the two asteroids that recently passed Earth. This represents the smallest meteor yet observed on Jupiter. An object of similar size was estimated to be responsible for the impact on Earth in 1994 near the Marshall Islands. Estimates “predict objects of this size to collide with our planet every 6–15 years” with significantly higher rates on Jupiter ranging from one to one hundred such events annually.
Clearly, amateur observations led to some fantastic science. Modest telescopes, “in the range 15–20 cm in diameter equipped with webcams and video recorders” can easily allow for excellent coverage of Jupiter and continued observation could help in determining the impact rate and lead to a better understanding of the population of such small bodies in the outer solar system.
