Water map: ESA / Herschel / T. Cavalié et al.; Jupiter image: NASA / ESA / Reta Beebe (New Mexico State University)

Distribution of water in the stratosphere of Jupiter as measured with ESA's Herschel space observatory and superimposed over an image of Jupiter taken at visible wavelengths with the NASA/ESA Hubble Space Telescope.

By Megan Gannon
Space.com

The stratosphere of Jupiter is filled with water delivered to the giant planet by a cataclysmic comet crash in 1994 that not only wowed scientists at the time, but spawned a legacy that is still delivering surprises today.

In July 1994, more than 20 broken-up pieces of Comet Shoemaker-Levy 9 slammed into Jupiter, captivating skywatchers and scientists alike.

Now, new research reveals that the comet collision not only gave Jupiter scars big enough to be seen from small telescopes on Earth; the ice-filled comet also dropped loads of water onto the atmosphere of our solar system's biggest planet, scientists say.  [See photos of Comet Shoemaker-Levy 9 hitting Jupiter]

Water vapor was first spotted in Jupiter's upper atmosphere by the European Space Agency's (ESA) Infrared Space Observatory in 1997. The spacecraft also found similar traces of water in the atmospheres of Saturn, Neptune and Uranus.

JPL / NASA / STScI

Jupiter vacuumed up the pieces of the disrupted comet Shoemaker–Levy 9 in 1994, but the impacts were a reminder of the danger faced by Earth.

On Jupiter, scientists knew that it could not have floated up from the inner part of the atmosphere because there's a vapor-blocking "cold trap" that separates Jupiter's stratosphere from the clouds in its troposphere below. But researchers remained unable to say where exactly the water came from.

Using ESA's Herschel space observatory, the most powerful infrared telescope ever sent into space, scientists recently mapped out the distribution of water vapor in Jupiter's upper atmosphere. They found that Jupiter's southern realm, where the comet hit, had two to three times more water than the planet's northern hemisphere. What's more, most of the water vapor was clustered around the Shoemaker-Levy 9 impact sites.

"The asymmetry between the two hemispheres suggests that water was delivered during a single event and rules out icy rings or moons as candidate sources," study leader Thibault Cavalié, of the Laboratoire d’Astrophysique de Bordeaux, said in a NASA statement.

"According to our models, as much as 95 percent of the water in the stratosphere is due to the comet impact," Cavalié added in a statement released by ESA.

These observations led Cavalié and colleagues to rule out other possible sources of the water vapor, such as a steady rain of interplanetary dust particles, which would have spread the vapor more evenly across the planet's upper atmosphere.

"All four giant planets in the outer solar system have water in their atmospheres, but there may be four different scenarios for how they got it," Cavalié explained. "For Jupiter, it is clear that Shoemaker-Levy 9 is by far the dominant source, even if other external sources may contribute also."

The research is detailed in the May issue of the journal Astronomy & Astrophysics.

Follow us @Spacedotcom, Facebook and Google+. Originally published on Space.com.

• Photos: Jupiter, the Solar System's Largest Planet
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• Comets: Formation, Discovery and Exploration

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Starry Night Software

This sky map shows the location of Jupiter and the moon in the night sky on Sunday, April 14, at 10 p.m. local time to observers at mid-northern latitudes.

By Joe Rao, SPACE.com

If the weather is clear on Sunday night, you can catch a potentially amazing sight: the planet Jupiter snuggling close to a thin crescent moon.

The celestial encounter will be visible in the western sky around mid-twilight, about an hour after sunset. At that time, the moon will be shining about one-third of the way up from the western horizon. It should be an eye-catching sight, with a slender sliver of a crescent moon shining right next to a bright star-like object — the bright planet Jupiter. 

Jupiter will appear to be about 3 degrees from the crescent moon. To understand how far apart they will appear in the sky, recall that your clenched fist held out at arm's length will measure 10 of those degrees. So you can use your fist to make a reasonable estimate of degrees either horizontally or vertically. 

In this case, Jupiter and the moon will appear rather close together; just one third of a fist apart. And partly because they will be the two brightest objects in the sky and partly because of their relatively close proximity to each other, both the moon and Jupiter will likely attract the attention of even those who aren’t consciously looking up at the sky. [Amazing April Night Sky Photos by Stargazers]

As the evening progresses, Jupiter and the moon will appear to descend down the sky, finally disappearing beyond the west-northwest horizon soon after 11:30 p.m. your local time.

Jupiter is still the brightest starlike object in the evening and the first to come out each night at dusk. It outshines the brightest true stars. In fact, it even rivals the brightest of all the stars, Sirius, which in early evening sparkles low in the southwest sky. When you are observing Jupiter, note how the planet shines with serene steadiness while Sirius, twinkles vigorously, as if struggling to match Jupiter's glory.

During April, Jupiter will slowly slip farther down into the glow of evening twilight in the west-northwest. And in about another month Jupiter will be setting right around the time evening twilight ends.  

This month, Jupiter is falling far behind Earth in the never-ending planetary race around the sun and it continues to move slowly eastward among the stars. Currently it can be found between the horns of the constellation Taurus the Bull. 

Because Jupiter takes nearly 12 years to orbit the sun, it spends about a year in each of the 12 zodiacal constellations. Jupiter moved into Taurus in mid-May of 2012 and will exit Taurus and move into Gemini the Twins late in June.

Editor's note: If you have an amazing picture of Jupiter and the moon or any other night sky view that you'd like to share for a possible story or image gallery, send photos, comments and your name and location to managing editor Tariq Malik at spacephotos@space.com.

Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for The New York Times and other publications, and he is also an on-camera meteorologist for News 12 Westchester, New York. Follow us @Spacedotcom, Facebookand Google+. Original article on SPACE.com.

• Jupiter Quiz: Test Your Jovian Smarts
• Lyrid Meteors and Partial Lunar Eclipse - Where & When In April 2013 | Video
• Best Telescopes for Beginners | Telescope Reviews & Buying Guide

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Starry Night Software

On Sunday, there will be a rare opportunity to observe Jupiter in daylight because it will be very close to the moon.

By Geoff Gaherty
Space.com

Have you ever seen Jupiter in daylight? This weekend, you just might get your chance.

Very few people have, but you could get an opportunity to join those elite ranks on Sunday. On that date, the moon will pass close to Jupiter, and can be used to locate the planet in the daytime sky.

Although the daytime sky looks like an unbroken blue blanket on a clear, sunny day, it is actually just as transparent in daylight as it is on a dark night. The difference is that much of the sunlight is scattered by the air molecules in our atmosphere, called Rayleigh scattering. Despite the overall blue cast this gives to the sky, stargazers can still easily see the sun and moon through it.

If you know exactly where to look — and have something to focus your eyes on — you can also see the brighter planets in a blue sky. Venus is easily observed, including the famous incident at Abraham Lincoln's second inauguration, when large numbers in the crowd saw Venus over the Capitol Dome. [Amazing Night Sky Photos for April]

Although it is much larger than Venus, Jupiter is more difficult to spot in daylight because it is farther from the sun. Because of its proximity to the star, it is not as well-lit. When Jupiter is close to the moon, it is easier to spot. The moon shows you where to look, and also gives your eyes something to focus on.

Starry Night Software

This close-up view shows the exact position of Jupiter relative to the moon at 2 p.m. EDT, the time of closest approach.

While Jupiter will be visible without optical aid on Sunday, it will be easier to spot first with binoculars. First locate the moon in the south-southeastern sky. Then, look slightly above and to the left of the moon to spot the tiny speck of Jupiter. Once you have spotted Jupiter in binoculars, try the greater challenge of seeing it without optical aid.

If you have a telescope, you can locate Jupiter in the same way.

Amateur astronomers whose telescopes have setting circles or GoTo computers can locate Jupiter any time without needing the help of the moon. Using these methods, you can also observe the planet Mercury and the bright stars Sirius and Procyon in full daylight.

Always remember to use extreme caution when using binoculars or a telescope when the sun is above the horizon. Be especially careful with GoTo telescopes, as these often take quite unpredictable paths across the sky and may catch the sun in passing.

Editor's note: If you snap an amazing photo of Jupiter in daylight or any other stargazing photo you'd like to share for a possible story or image gallery, please contact Managing Editor Tariq Malik at spacephotos@space.com.

This article was provided to Space.com by Starry Night Education, the leader in space science curriculum solutions. Follow Starry Night on Twitter @StarryNightEdu. Original article on Space.com.

• Jupiter Quiz: Test Your Jovian Smarts
• Look Up! Night Sky Guide for April 2013 (Sky Maps)
• 10 Best Space Apps in the Universe

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Starry Night Software

On Sunday night, March 17, say farewell to the winter sky in the western twilight.

By Joe Rao, SPACE.com

On Sunday evening, revelers can cap their St. Patrick’s Day by enjoying a view of a rendezvous involving two of the brightest objects in the night sky: the moon and the planet Jupiter. 

About 45 minutes after sunset on Sunday, the eye-catching celestial duo will be visible in the southwest sky, roughly two-thirds up from the horizon to the point directly overhead (called the zenith).  

The moon will be a wide crescent at the time, 34 percent illuminated by the sun, and will sit below Jupiter. At its closest pass — which will occur at around 10:30 p.m. local daylight time along the U.S. East Coast, and around 7 p.m. local time for the West Coast — Earth's natural satellite will be just 2 degrees from the giant planet. (For reference, your clenched fist held at arm's length measures about 10 degrees.)

After its closest approach, the moon, moving at its own apparent diameter per hour, will appear to slowly move away from Jupiter to the east (left). [Amazing Night Sky Photos by Stargazers (March 2013)]

Even without the moon, Jupiter readily attracts attention. It’s the brightest "star" of the night, coming into view high in the southwest during the early stages of twilight. The first-magnitude star Aldebaran flickers into view next, about 5 degrees to the lower left of Jupiter, its orange color helping it to stand out from the deepening dark-blue sky.

Last to appear are the famous Pleiades and Hyades star clusters as the sky darkens from purple to black.  The entire array of the moon, planet, bright star and star clusters sits within the constellation of Taurus (The Bull).

Binoculars are perfect for observing the whole Taurus get-together. Even the most ordinary pair will show dozens of Pleiades and Hyades stars, and at least one, two, or three of Jupiter’s four bright Galilean moons (Ganymede, Callisto, Io and Europa).

Be sure to check out Jupiter on the evening of March 24, when any small telescope will show it closely flanked above and below by two seventh-magnitude background stars in Taurus, masquerading as an extra pair of renegade Galilean satellites.   

In a telescope, Jupiter is best observed during early evening when it’s still high and its image reasonably calm. Viewing at such times shows the king of planets as a great big belted ball with tantalizing glimpses of detail. 

As the evening grows late, the whole assemblage wheels lower in the west and sets soon after midnight.

Editor's note: If you snap an amazing photo of Jupiter and the moon in the night sky, or any other celestial object, and you'd like to share for a possible story or image gallery, please send images and comments, including location information, to managing editor Tariq Malik at spacephotos@space.com

Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for The New York Times and other publications, and he is also an on-camera meteorologist for News 12 Westchester, New York. Follow us @Spacedotcom, Facebook or Google+. Originally published on SPACE.com.

• Night Sky Observing Guide: March 2013 (Sky Maps)
• Skywatchers Can See Planets, Star Clusters This March | Video
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Copyright 2013 SPACE.com, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

Joe Shuster / Lake County Astronomical Society

Astrophotographer Joe Shuster sent in a photo of Comet Pan-STARRS and the crescent moon taken in Salem, Mo., on Tuesday.

By Geoff Gaherty
Space.com

If you step outside shortly after twilight on Sunday night, you may catch a spectacular heavenly panorama involving the moon, a planet and a visiting comet.

High in the southwestern sky, weather permitting, observers can see the moon riding close by brilliant Jupiter, locked in a close conjunction. The Comet Pan-STARRS, meanwhile, rounds out the evening sky view low on the western horizon.

The moon will be a narrow crescent, two days short of first quarter, and you should be able to see its darkened portion faintly illuminated by earthshine, sunlight reflected from the sunlit Earth.

Jupiter is now receding toward the far side of the sun, but it is still the brightest object in the sky other than the moon.

The moon and Jupiter both stand in front of the vast Hyades star cluster, with the red giant star Aldebaran nearby. Just to their right is the brighter, more compact Pleiades star cluster.

Off to their left is the familiar constellation Orion, with its two contrasting, first-magnitude stars, red Betelgeuse and blue-white Rigel, along with its jaunty belt of three equal stars. Further to the left is the brightest star in the night sky, Sirius.

Starry Night Software

On Sunday night, March 17, say farewell to the winter sky in the western twilight.

To the right of the moon and Jupiter and low on the horizon, is the downward-pointing "finger" of Comet Pan-STARRS, a special visitor to our skies this month. [How to see the comet]

Comet Pan-STARRS, officially known as C/2011 L4 (Pan-STARRS), was discovered in June 2011 and is one of several comets gracing the night sky in 2013. The Comet Lemmon has been visible in recent weeks by stargazers in the Southern Hemisphere. In late November, the incoming Comet ISON may potentially put on a dazzling display when it makes its closest approach to the sun, NASA scientists and astronomers have said.

As Pan-STARRS, the moon and Jupiter move toward setting on the western horizon, the skies of spring are rising in the east: Leo, Virgo and Bootes, with their bright stars Regulus, Spica and Arcturus —and, in their midst, the ringed wonder planet, Saturn.

This is the sort of vista on which stargazers thrive, available freely to all who will turn their eyes to the darkened skies. It is sad that so many on Earth see only a dim ghost of this view because light pollution denies them their stellar heritage. This weekend, try to seek out darker, unpolluted skies so that you, too, can share in the beauty of the night sky.

Editor's note: If you snap an amazing photo of the moon and Jupiter's close conjunction in the night sky, or any other celestial object, and you'd like to share for a possible story or image gallery, please send images and comments, including location information, to Managing Editor Tariq Malik at spacephotos@space.com.

This article was provided to Space.com by Starry Night Education, the leader in space science curriculum solutions. Follow Starry Night on Twitter @StarryNightEdu and follow us @Spacedotcom, Facebook  or Google+. Original article on Space.com.

• Comet Pan-STARRS and the Moon: Spectacular Stargazer Photos
• 6 Stellar Places for Skywatching in the US
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