The lowest layer of the atmosphere, the troposphere, is a mix of cloud and haze composed mostly of hydrogen and helium with traces of ammonia, ammonium hydrosulfide, and water.  The upper ammonia clouds are sectioned into a number of bounded zonal bands parallel to the equator.  These are the bands we see from Earth, and they alternate in color.  The dark bands are called belts and light bands are called zones.  Zones, which are colder than belts correspond to rising gas.  Belts consist of gas descending to lower altitudes.  The lighter color of the zones comes from ammonia ice. It’s still uncertain what gives the belts their darker colors.

* * * Highly Recommended * * *

Ready to see deeper into the night sky? Stargazing for Beginners takes you on an easy-to-follow binocular tour of the stars and main constellations. No telescope required! Click here to learn more…

The names of the belts and zones visible on Jupiter. Note that "south" on Jupiter refers to pole of the planet that points south on Earth, and vice versa.

Like the trade winds on Earth, the belts and zones of Jupiter are mostly constant and remain stable over centuries.  But Jupiter’s atmosphere shows an amazing amount of active phenomena, including band instabilities, cyclones and anticyclones, storms and lightning.  Giant vortices reveal themselves as large red, white, or brown ovals.  The most famous is the Great Red Spot (GRS).  Located in Jupiter’s southern hemisphere and as large as several Earths, the GRS is the largest known vortex in the Solar System. While it brightens and fades from time to time, the GRS has persisted for at least three hundred years.

The GRS and other phenomena rotate with the planet, so they are not always visible from Earth.  You can find out when the GRS is visible using this handy calculator from Sky and Telescope: http://bit.ly/rbpw2p

Another spot called “Oval BA” formed in 2000 from smaller three white ovals.  The Oval BA is a pale red spot south of the GRS and about a third its size.

Even with a 3-inch scope, you can see the major belts, zones, and the Great Red Spot.  Use high magnification, but not too high.  How much depends on the quality of your optics and your seeing conditions.  It’s a trade off between image size and quality.  Some nights you might get away with 200-300x or more, other nights only 100x. Look a little at a time to avoid fatigue, breathe deep, and don’t rush it.  Try to sketch each detail you see… it’s a great exercise to help sharpen your seeing skills.  And take a close look at the excellent images of Jupiter from Chris Goh at the top of this page to see the belts, zones, and GRS as imaged with a 14″ telescope (and a lot of skill) in late August 2011.

Like all meteor showers, the Orionids occur as the Earth passes through the debris-strewn path of a comet, in this case, Halley’s Comet.  The meteors are simply tiny bits of ice and dust that fell away from the comet and ran into our atmosphere.  As in all such showers, the meteors appear to originate from a point in the sky called the radiant.  For this shower, the radiant lies in the constellation Orion.  Hence the name.

See above for an image of the Orionids in 2006 (here’s the original link… http://apod.nasa.gov/apod/ap061023.html)

The Orionids run from October 17-25, with the peak predicted for early on October 21.  The meteors will be visible to observers in both hemispheres.  Just look up anywhere into the sky with your unaided eye and wait.  You’ll see some eventually.  If you can trace back the direction of a meteor to the radiant in Orion, that means you likely saw an Orionid.  If not, you simply saw a random meteor.  You’ll likely see more meteors after midnight, when the Earth turns into the debris field of Halley’s famed comet.

At its peak, the Orionids show just half as many meteors as August’s Perseids, but they are still an impressive sight.

Watching a meteor shower is a pleasant way to spend a night.  But it’s also fairly easy to photograph a meteor shower.  All you need is a tripod and a camera that allows you to open the shutter for several minutes.  A digital SLR camera is ideal.  Point the camera anywhere in the sky, open the shutter, and wait.  This is one of the easiest types of astrophoto you can take.

To learn more about taking your own photos of meteor showers and other sights in the night sky, simply click here…

The Draconids occur each year at this time when the Earth passes through a stream of debris left from periodic Comet Giacobini-Zinner.  While it’s usually a spartan meteor shower, the Draconids have flared up from time to time.  In 1933 and 1946, observers reported thousands of meteors per hour, so this modest shower became a meteor storm.  There was also a good show in 1988.  Astronomers suspect we’re going to hit a thick patch of debris this year, which means more meteors.

The Draconids are predicted to peak from 19:00 to 21:00 UTC on October 8.  So that’s 8 p.m. to 10 p.m. local time in the U.K., an hour later in northern Europe, and 3 p.m. to 5 p.m. Eastern Daylight Time in North America (ie. during daylight).  But again, the timing is not set in stone, so take a look as soon as it’s dark and keep looking as long as you can.

The location of the radiant of the Draconid meteor shower (click to enlarge).

Where to look?  The meteors will appear to streak out of a point in the far-northern constellation Draco (see image above).  But they will appear anywhere in the sky.  So just look up and hope for the best.

And enjoy the show…

Sunspots have been hard to find these past few years.  The number of spots rises and fall on an 11-year cycle, and the next sunspot maximum should occur sometime next year.  But this cycle was slow to start and fairly meagre.  So this spot is one of the best in years.

Here’s a current view of the sun right now… the big sunspot group is labelled 1302:

Image of the Sun in white light at 17:00 GMT on September 27, 2011 (from http://sohowww.nascom.nasa.gov/sunspots/)

You can see the sunspots for yourself if you have the proper solar filters and a telescope.  If you have neither, try a poking a hole in a piece of thick paper and projecting the sun’s inverted image on a second piece of shaded paper 2-3 feet away.  You may see the sunspots on the Sun’s small image.  But remember… don’t look directly at the Sun without a filter!

You can learn more about solar filters here…

As often happens with sunspots, solar activity has increased over the past week and a coronal mass ejection occurred over the weekend.  This giant spray of charged particles is reaching the Earth now, and it may lead to inspiring views of aurorae tonight and tomorrow.  So take a look.

You can follow this sunspot group over the next many days as the Sun’s rotation takes it slowly out of view.

And you can click here to get a refresher on sunspots…

Comet Elenin certainly had promise.  Though its nucleus was small — just 3-4 km across –astronomers figured the comet’s orbit would bring it within 45 million miles of the Sun by September 10, and within just 22 million miles of the Earth by October 15.  That usually means a comet that appears bright and fast moving as it swings around the Sun.

But the prediction of has fallen apart, alas.  And so, perhaps, has the comet!

Astronomers watched Elenin unexpectedly fade late last month by a full magnitude last month.  What’s worse, its tiny nucleus now appears elongated and fuzzy (see image above, and video below)  That’s a signature of a comet breaking into pieces and possibly disintegrating.  Here’s a video of the comet’s nucleus changing from star-like to diffuse over the course of many days…

Experienced comet watchers believe Elenin may not survive its close encounter with the Sun in the coming days, and may simply break up and disappear.  We’ll know soon.

Right now, the Comet Elenin has dimmed to less than magnitude 10 and appears too close to the Sun to observe with small Earthbound telescopes.

So we may not get to see this comet.  Which is too bad because it came from a long way.  Elenin was likely a distant resident of the Oort Cloud, and spent most of its long, lonely life nearly a light year from Earth, about 1/4 the distance to the nearest star.

If Comet Elenin is finished, the misguided end-of-the-world bloggers who believed it would cause doom and disaster on Earth in 2012 will have to find something else to worry about.  (Frankly, the state of the European banks is far scarier right now than anything in the heavens).

And of course, we have a consolation.  Comet Garradd remains visible in binoculars and a small scope.  Find it this weekend about halfway between the 3rd-magnitude star Albireo at the nose of Cygnus, the Swan, and the 2nd magnitude star Rasalhague in Ophiuchus (see below).

Comet Garradd as seen on September 23. The comet lies about halfway between Albireo and Rasalhague.

* * * Now at Stargazer University * * *

A crash course in stargazing!  This collection of the best 111 articles from the first three years of One-Minute Astronomer shows you how to see and enjoy the sights of the solar system and deep sky.  Ideal for beginners, experienced stargazers, and armchair astronomers.  Click here to learn more.

Scientists believe Vesta is worthy of close inspection.  Vesta is the second-most massive body in the asteroid belt, a vast and tenuous collection of thousands of tiny worlds between the orbits of between Mars and Jupiter.  The asteroid belt is likely a “failed planet”, a mass of scattered debris that couldn’t pull itself together because of Jupiter’s meddling gravitational influence.  But the composition of the asteroids may be much like the rocky planets major of our solar system like Earth and Mars.  And asteroids like Vesta may reveal clues to the conditions in the early solar system.  That’s what the Dawn spacecraft will help find out.

While the view from Dawn is spectacular, NASA will guide the craft into an even lower orbit around the asteroid in October, before moving it on to meet the largest asteroid Ceres in February 2015.  It will make for excellent viewing for armchair stargazers…

Few stargazers take the time to observe asteroids, but that just makes them all the more worth seeing.  Most asteroids are very faint, it’s true.  But Vesta and the larger Ceres are fairly easy to find when their nearly opposite the Sun as they are now.

Vesta lies presently in the constellation Capricorn in the southern part of the zodiac.  The map below shows Capricorn as seen at 10 p.m. in the northern hemisphere this month; in the south, it appears nearly overhead.  The lower map shows more precisely the current position of Vesta near the star ψ (psi) Capricorni.

The asteroid Vesta in southern Capricorn, as seen in late September 2011 (click to enlarge).

The position of Vesta near the star psi Capricorni (click to enlarge).

At magnitude 7, this asteroid is easily visible in binoculars as a star-like point of light.  So go have a look for yourself at this rocky — and slightly less mysterious  — little world.

Over the next many years, slow-moving Uranus lies in the constellation Pisces.  To find the planet, first look towards the southeast at 10-11 p.m. for the “Great Square” of Pegasus.  Then look just southeast of the Great Square for the squashed circle of stars called the “Circlet of Pisces”, which spans about 5 degrees of sky.  The map below helps you get oriented.  In the southern hemisphere, the view is similar, but the Circlet of Pisces lies nearly due east in the mid-evening hours.

******** From Stargazer University ********

Now 33% off until September 30, 2011!  Around the Moon in 28 Days takes you on a full tour of the Moon during the month.  Learn the seas, highlands, craters and mountains of the Moon, and get a glimpse of the solar system in its earliest days.  Click here to learn more…

The location of Uranus near the Circlet of Pisces as seen in the SE sky at 11 p.m. in mid-September (click to enlarge)

Over the next months, the planet Uranus is just east-southeast of the Circlet.  It’s nearly invisible without optics, and will appear star-like in binoculars.  The more detailed and close-up map below will help you find Uranus relative the the Circlet.  Over the next many weeks, the planet lies on a line east of two stars in the Circlet called 6 Piscium and 19 Piscium, a distance from 19 that’s about the same as the distance from 6.  The maps below shows you what I mean…

The location of Uranus in September 2011, about 5 degrees due east of the Circlet of Pisces (click to enlarge).

To see the disk of this distant world, you’ll need a telescope.  Find the correct area with a low-power eyepiece.  At less than 50x, the planet will appear star-like.  But increase the magnification, and you’ll notice one of the stars swells to a tiny disk.  That’s Uranus.  Increase the magnification as high as you can, which is the same technique William Herschel used to determine this was a planet, not a star.  You may see a faint cyan color on the disk.

Uranus presents no features, and is a humble object in a small scope compared to mighty Jupiter and Saturn.  But it’s still a splendid feeling to find this distant giant, which itself remained mysterious until Voyager 2 whirled by the planet just 25 years ago.

Bonus Object: While you’re in the area, look for the star 19 Piscium (see the map above).  This is a dull and very red carbon star where material from the core is dredged up to the surface to absorb all but red and infrared light.  The star is also cataloged as TX Piscium.  At magnitude 5, the star is an easy target in binoculars or a telescope.

Uranus was discovered by the great William Herschel in 1781, an accomplishment that cemented his reputation as the greatest amateur astronomer of his day and launched his professional career with the patronage of England’s King George III, himself a dedicated amateur astronomer.

Politics dominated the debate over the name of the new planet.  Possible names included “George’s Planet” and “George’s Star”, after the English king.  But the neutral name of Uranus was chosen by Johann Bode in honor of the Greek god of the sky.  Uranus remains the only major planet not directly named after a Roman god.

As an ice giant, Uranus, along with Neptune, consists mostly of icy water, ammonia and methane, unlike the larger “gas giants” Jupiter and Saturn which are mostly hydrogen and helium.  The blue green color of these ice giants comes from the thin layer of hydrogen and helium floating above the heavier ices, and there are scant lighter cloud bands of methane and trace hydrocarbons.

With just 1/400th the sunlight of Earth, Uranus is a dim, cold world.  Its cloud-top temperature of just 50 degrees Kelvin (-223 Celsius) is the coldest of all major planets– Neptune generates more internal heat than Uranus.

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Tired of just reading about the stars? Stargazing for Beginners takes you on an easy-to-follow binocular tour of the stars and main constellations. No telescope required! Click here to learn more…

The five largest moons of Uranus

Another odd feature… Uranus rotates on its side.  Its otational axis is inclined 98 degrees to its orbital plane, which suggests it received a mighty thump in the early days of the solar system that knocked the planet on it side.  As a result, the northern and southern hemispheres of the planet remain in darkness for decades at a time. The thin, coal-black rings of the planet likely formed after the planet was knocked over.  Same with the little clutch of small moons of Uranus, the largest of which are named after the Shakespearean characters Titania, Oberon, Miranda, Umbriel, and Ariel.

At magnitude 5.8, Uranus is visible, barely, without a telescope.  But the planet did not make a sufficient impression upon ancient stargazers to be noticed as a planet.  Even in the early telescopic age, the astronomers John Flamsteed and Pierre Lemonnier observed Uranus on dozens of occasions before Herschel’s discovery.

But if you manage to enjoy a little clear sky over the next few days, look again for Comet Garradd near the lovely little “Coathanger” asterism.   The map below will help you find it, just to the northwest of the constellation Sagitta.

Comet Garradd near Coathanger cluster (click to enlarge)

And if you’re clouded out, you can still enjoy this little video of Comet Garradd created by subscriber Stephen W.  It was created over a 2 hour period as the comet passed the star cluster M71 last week.

Comet Garradd Video (click to view)

Stephen used a Celestron CGEM 800 with a Meade f/3.3 focal reducer and DSI II camera.  Each frame is made from a one-minute exposure.  A light pollution filter was used to reduce the effect of nearby streetlights.

Pretty good, don’t you think?

And I certainly have a long list of deep-sky sights to observe…

In fact, as the publisher of One-Minute Astronomer, I’m often asked for suggestions of what to look at with a small telescope.   After more than three decades of stargazing, I do have many favorites.  Especially this time of year.  You can learn more about my seasonal must-see list right here. You won’t find a list quite like this anywhere else…

One of the most unusual sights for stargazers to check out this month is the bright asteroid Vesta cruising through the constellation Capricornus.

At magnitude 5.8, the asteroid is easily seen in binoculars as it approaches opposition to the Sun on August 6.  Seeing the asteroid now holds even more meaning as NASA’s Dawn spacecraft has taken up orbit around Vesta and is sending back many fine images of this mysterious world (see image above).

Here’s a general map to help you locate Vesta tomorrow at midnight.

The location of the asteroid Vesta in Capricorn on July 30, 2011, looking southeast at midnight (click to enlarge).

For a more general map to help you follow Vesta (and the larger asteroid Ceres) over the next few months, check out this excellent finder chart from Sky and Telescope.

That’s it for today.  Let’s all hope for clear skies this weekend…