A Sky Without Stars

A Sky Without Stars
by Dave Adalian

The greatest bane of astronomers is encroaching light.

When the Moon is full or the neighbor leaves his porch light on all night the splendor of the starry sky is ruined.

Fortunately, in Tulare County (Calif.) we can always retreat to the countryside and the vast open acres of croplands and grasslands.

My favorite place to remove myself from the lights of an increasingly bright Central (San Joaquin) Valley is the lonely cattle country of Yokohl Valley east of Rocky Hill.

Out among rolling hills covered in brown grass baked in the heat the sky is still a jewel encrusted dome, where thousands of lights dazzle on a velvet backdrop. Just minutes from downtown Visalia (Calif.), where the star clouds of the Milky Way are never seen, our home galaxy stretches itself from horizon to horizon so beautifully it pulls the breath from your body.

Just five miles down a winding two-lane road there is isolation almost complete, where seeing more than two cars in a night is heavy traffic. Owls cry in the dark. Coyotes yip and laugh and howl to one another among the silhouettes of ancient oak trees standing sentinel on far away ridge tops. It is so quiet you can hear the clicking screech of bats finding their way through blinding inkiness.

Yokohl Valley is a place that I hold dear, and it has been my secret retreat for a dozen years. Now, I’m sharing it with you.

You’d better get there soon.

I’ve been selfish with my hideaway, but no more. As many people as can come should see the wonder of this hidden foothill valley before it’s gone.

An international corporation has decided to turn my secret Eden into a retirement community. If our leaders lend support to this idea, the splendor of Yokohl Valley will soon be no more.

The land will still be there. The stars will still shine overhead, too, but we’ll never see them in the glow of a thousand shining street lights.

Come out to Yokohl Valley before the Sun sets and let the blazing summer turn into cool, dark night around you. Let the sweet smell of wild grasses baked in the sun fill your senses. Hear nighthawks’ screams echo among the rocks and feel the chill on your skin as the coyotes call to one another across the empty spaces.

See the stars shining over this doomed valley before they’re lost forever.

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Join the Tulare Astronomical Association for a public star party this Friday, 9:30-11:30 p.m., at the Purcell Observatory, 9242 Ave 198, south of Tulare (Calif.) and 2.1 miles west of Hwy 99. Information: http://starry-starry-nights.blogspot.com/.

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This column originally appeared in the Visalia (Calif.) Times-Delta and Tulare (Calif.) Advance-Register on Thurs., July 13, 2006.

Solstice Marks Summer's Start

Solstice Marks Summer's Start

by Dave Adalian

Soaring temperatures may make it seem like summer has already arrived, but even so the astronomical start of the season is still nearly a week away.

Summer, according to astronomers, begins with the solstice, the moment when the Sun reaches the northernmost point above the celestial equator, an imaginary line above Earth’s equator that divides the sky into northern and southern hemispheres.

The solstice is also marked by the rising and setting of the Sun as far north on the horizon as it can reach. If you watched the sunrise each day, you’d notice the Sun swings back and forth slowly along the horizon until it reaches its northernmost point in June and its southernmost point in December. Solstices mark the days when the Sun stops then reverses direction. In Latin the word solstice literally means Sun (Sol) stands still (sistere).

The Sun will reach the summer solstice on Wednesday at 5:26 a.m., just a few minutes before it rises, and summer 2006 will be underway.

Even if you didn’t have the Sun to set your calendar by, the stars could serve in its stead.

It’s a sure sign spring is at an end when the constellation Leo is standing on its head above the western horizon just after the Sun goes down. Find it by looking for the backward question marking the lion’s head and the triangle of stars that is its haunch.

Looking north, the Big Dipper of Ursa Major is propped up with its handle high in the air. Following the curve of its tail and extending it past the end of the handle and across the zenith takes us to bright orange Arcturus in the constellation Bootes. This star is the brightest in the summer sky and the northern hemisphere.

After arcing to Arcturus, continue along the curve from the Dipper and speed on to Spica, the brightest star in the Virgo. Don’t make the mistake of confusing Spica with bright Jupiter which sits just up and to Spica’s left.

The eastern sky holds a trio of bright stars so tied to summertime the shape they draw is named after the season. Deneb in the north, Altair in the south and Vega above them form the Summer Triangle. One of the brightest portions of the Milky Way spills through the center of the triangle and is visible even from urban backyards. For an even better view, head for the darker skies outside the city.

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This column originally appeared in the Visalia Times-Delta on Thurs., June 15, 2006.

The June Moon

I've been playing the shutter bug this month with my new camera. My subject has been the Moon, and here are the results:

http://dave.adalian.googlepages.com/thejunefullmoon

Rain?!?

Well, it's an official record. As I type this it is raining after an entire month of clear skies. This makes eight months in a row the Tulare Astronomical Society's monthly star party has been rained or fogged out. We'll try it again in June, folks...

You can check the hour-by-hour weather at the Arthur L. Purcell Observatory by clicking the link on the right side of this page.

Manmade ‘Stars’ in Summer Skies

Manmade ‘Stars’ in Summer Skies

by Dave Adalian

If you’re gazing skyward on a warm night in late spring or summer and it appears one of the stars has come loose from its moorings to drift across the heavens there’s no need to worry. You’re not imagining things.

What you’re seeing isn’t a star. Instead it is something far closer to home, a satellite.
It used to be the only thing in orbit around the Earth was our moon, but with the first successful rocket launch into low Earth orbit by the former Soviet Union back in the middle 1950s everything changed.

Since then, mankind has peppered the heavens with more than 27,000 artificial satellites, from the huge International Space Station down to bolts, lost tools and bits of discarded trash, even an unlucky astronaut’s glove, all left to drift in space until Mother Earth’s relentless gravity finally coaxes them back for a fiery reentry into the atmosphere.

Of those various bits of stuff we’ve heaved into the sky, some 9,000 of them are still up there, and of those several hundred of are visible to the naked eye.

When you find one of these star-like pinpricks making its stately way through the heavens, what you’re seeing is actually reflected sunlight shining off it. How bright a satellite appears depends on several factors, including how high above the Earth it orbits, its size and how well it reflects sunlight.

During the shorter nights of the warmer months, the tilt of the Earth’s northern hemisphere toward the Sun not only causes summer’s weather, it also causes Earth to cast a shorter shadow. This means more of the satellites soaring overhead are exposed, which makes this the best time of the year to see them.

It also helps that the warmer weather makes it more likely would-be satellite hunters will venture outside.

Among the brightest of satellites is a group known as the Iridium Constellation. Dozens of these communications satellites surround the Earth, producing extremely bright flares on a regular basis.

Another favorite bright target of satellite seekers is the Hubble Space Telescope, which will be making a series of predawn passes throughout May before becoming an evening object again in June.

You can find out when the Iridium satellites, the HST and the ISS will be visible overhead where you live by visiting www.Heavens-Above.com.

The site also provides predicted appearances for dozens of other satellites, along with maps and observing tips.

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The column appeared originally in the Visalia Times-Delta on May 18, 2006.

The Stars of Winter Fade

The Stars of Winter Fade
by Dave Adalian

With the spring rains finally starting to taper off it’s a good time to get reacquainted with the night.

As April comes to a close, the bright constellations of the winter sky drop quickly over the western horizon after darkness takes hold so you’ll need to catch them around 9 o’clock.

The most recognizable of the winter constellations, Orion, is lying low almost due west. At its most basic, Orion is a great rectangle of bright stars, including brilliant Rigel, at the western corner, and the red giant Betelgeuse sitting at the most easterly. In the center of Orion’s familiar shape are the three belt stars, Alnitak, Alnilam and Mintaka.

These three equally bright white suns form a straight line at Orion’s waist pointing the way to the sky’s brightest star, Sirius. Extend the line of the belt to the south and you’ll find Sirius shimmering in the southwest. Sirius, which sits in the constellation Canis Major or the Big Dog, is the brightest star as seen from Earth.

Following the belt stars of Orion in the other direction leads to the V-shaped face of Taurus the Bull. This gathering is actually an open cluster of associated stars known as the Hyades. Brightest among them is the red giant star Aldebaran, however, Aldebaran isn’t actually a member of the Hyades but only appears to be sitting in front of it from our vantage.

Aldebaran is sometimes called the Bull’s Eye, but its name translates as “the Follower.” It earned the moniker because it seems to trail the Seven Sisters of the Pleiades through the sky. You’ll find the Pleiades just north of the Hyades.

Above the Hyades and the Pleiades is a ring of five bright stars in the constellation Auriga the Charioteer. This group is an ancient one known as Rukubi the Chariot to the Babylonians.
The most northerly star in the ring is also its brightest, Capella the She-goat.

Southeast of Auriga, just above Orion, are the twin stars Castor and Pollux of Gemini.

All of these constellations are mainstays of winter, but spring is in full bloom now and a sure sign of this is Leo riding high overhead. To find the lion search for a reversed question mark that outlines Leo’s mane. Nearby is a triangle of stars that is Leo’s hindquarters. The brightest of these is Denebola, the “tail of the lion.”

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This column originally appeared in the Visalia Times-Delta on Thursday, April 20, 2006.

Stargazing Without Stars

Stargazing Without Stars
by Dave Adalian

The rain we’ve been getting for the last two months is great if you’re a farmer or a frog. But if you’re an amateur astronomer eager to see the night sky the constantly cloudy skies are enough to make you want to do an anti-rain dance.

Time spent waiting for the rain gods to grow tired doesn’t, however, have to be time spent away from the stars if you’ve got an internet connection.

Amateur astronomy is a hobby for those of us who think all things scientific are pretty nifty, in other words geeks, and the internet falls squarely in our zone of interest. That means there are tons of astronomical websites available to keep the soggy stargazer busy on cloudy nights.

If you’re looking for the latest news of the night sky, you can point your browser to any one of dozens of news services. Among the more popular are the home of Astronomy Magazine, astronomy.com, and the home of Sky and Telescope Magazine, skyandtelescope.com.

Services like SpaceRef.com and Space.com will put the latest in space exploration and astronomy news in your email in-box on a daily basis when you sign up at their homepages.

For discussing the latest news about the heavens with fellow astronomers there are some great online forums. CloudyNights.com is a popular message board, and a host of similar discussion groups are available at http://groups.yahoo.com. Some of the more popular groups there include Astronomer, Starry Nights and WannaBeAstronomers, a group for those just dipping their toes into the Milky Way.

Also at Yahoo! Groups is CenCalAstro, a group of Tulare, Kings, Kern and Fresno county amateur astronomers who post news of local sky watching events.

If you’re looking for help planning a stargaze once the weather clears, head to SkyMaps.com, where you’ll find printable maps of the night sky for the current month, along with lists of recommended targets for the naked eye, binoculars and telescopes, as well as tips for making the most of a night’s viewing.

You can also find out what artificial lights will be up in the night sky at Heavens-Above.com, a site that alerts readers about what satellites--including the International Space Station, the space shuttle when it’s aloft and the Hubble Space Telescope--will be visible and when.

Finally, if you just like to look at pretty pictures, then the Astronomy Picture of the Day is the place for you. Check it out at antwrp.gsfc.nasa.gov/apod/astropix.html.

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This column originally appeared in the Visalia Times-Delta on Thursday, March 23, 2006.

The Underside of Clouds

Unless we get a radical clearing of the sky before this evening, which the weatherman says isn't going to happen, we'll being giving the Feb. 17 star party a miss. Sorry, folks! I was looking forward to it, too, but I'm not driving all the way to the observatory just to look at the underside of clouds...

Since you already set aside the time, why not head over to the College of the Sequoia's for tonight's SVPC Presents the Talk of the Town: Global Warming and the Central Valley? The presentation is at 7 p.m. in Lecture Hall 350 (behind the COS Theater), 915 S. Mooney Blvd. in Visalia. The speaker will be Erin Rogers of the Union of Concerned Scientists.

Earth’s Bright and Angry Sister

Earth’s Bright and Angry Sister
by Dave Adalian

That bright light shining in the east during early morning hours this spring isn’t a UFO, and it’s not an airplane coming in to land, either.

It’s Earth’s sister planet, Venus.

Of the four inner rocky planets of our Solar System, Venus is the most like our home--but there’s a world of difference, too.

Venus is almost exactly the same size as Earth, just over 400 miles slimmer at the equator, and boasts 80 percent of our planet’s mass. Venus and Earth (and Mercury and Mars, too) are also made of pretty much the same stuff, unlike the outer gaseous planets, and at one time Venus had its own water.

This is where the similarity stops.

Venus is about one third closer to the Sun on average than Earth, and solar heating caused by this proximity kept the water on Venus from becoming a liquid. Having an atmosphere comprised of mostly water vapor led to an extreme greenhouse effect, with the trapped heat eventually destroying Venus’s water and driving huge amounts carbon dioxide from the surface rock, pushing the heat even hotter.

Today, temperatures on Venus range from lows in the 260-degree range with highs approaching 900, and the atmospheric pressure is 90 times that of Earth at sea level. These conditions are widely, famously and rightly reported as being hot and nasty enough to melt lead.

Adding to Venus’s oddness is its retrograde rotation. While the other planets turn counterclockwise as seen from above their north poles, Venus rotates clockwise, meaning on Venus the Sun rises in the west. But, you’d have to wait a long while to see it.

Venus, because it is closer to the Sun, has a year that is only 225 Earth days long, but it takes 243 days to turn on its axis. On Venus, a day is longer than a year.

As 2005 ended, Venus put on a months-long display as the spectacular Evening Star, dazzling in the west during the hours after sunset.

Now, she’s back, only this time in her incarnation as the Morning Star, shining her brightest for 2006 tomorrow during the hours before dawn when early risers will find her hanging jewel-like in the predawn eastern sky.

This apparition will last into May, when we should be hearing much more about Venus and its bright atmosphere as the European Space Agency’s Venus Express probe reaches our sister planet and begins returning data on the makeup of its stifling conditions.

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This column appeared originally on Feb. 16, 2006 in the Visalia Times-Delta.

The Other King of the Planets

The Other King of the Planets
by Dave Adalian

While Jupiter is regarded as king of the Roman gods and of the planets, he’s actually got a rival in the night sky, Saturn. But, it’s all in the family.

Saturn’s counterpart in Greek mythology, Cronus, was king of the Titans, who were the beings that ruled the Cosmos before the birth of the gods. It was foretold that one of Cronus’ children would replace him as ruler of all that is, but Cronus had a plan to stay in power. He decided to eat his offspring as they were born to his wife Rhea.

Problem solved.

But it wasn’t. When Rhea gave birth to Zeus, the Greek equivalent of Jupiter, instead of giving Zeus to Cronus she gave him a rock, which Cronus swallowed instead. After Zeus was raised by a magic goat, he forced his father to cough up the other gods and took his father’s throne.

Cronus, or Saturn as we know him, is actually larger than his son Jupiter, at least if you count his rings. While Jupiter is some 88,000 miles wide, Saturn’s ring system spans twice that distance at 176,000 miles. Saturn’s disk is 75,000 miles wide.

Saturn, which is the sixth planet out from the Sun, will be at its closest and brightest for the year on the night of Friday, Jan. 27.

Right now, Saturn is in the constellation Cancer, rising just as the Sun is setting. By midnight it reaches its highest point in the sky, shining bright and yellow. Even though Saturn appears so bright, it will still be 755 million miles away when it makes its closest approach to Earth next week.

Besides being the only planet in our system with a set of rings visible from Earth, Saturn is also less dense than regular water. That means if there was an ocean big enough to dunk it in Saturn would float.

Out of the more than 140 moons in the Solar System, Saturn’s moon Titan, at 3,200 miles wide, is the second largest, just 80 miles more narrow than the largest, Jupiter’s Ganymede.

Titan and several of Saturn’s other moons and the beautiful rings are visible from Earth through a telescope, but the planet is still a wonder even without one. This will be especially true during the first few days of February when the ringed planet slides into a bright star cluster in Cancer known as the Manger.

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This column appeared originally in the Visalia Times-Delta on Jan. 19, 2006.

Long Nights full of Planets

Long Nights full of Planets
by Dave Adalian

For the price of a little midnight oil, along with some luck and a bit of persistence, the naked-eye planets can all be viewed in a single night this week. But, you’ll have to move quickly and be eagle-eyed.

The easiest of the nighttime wanderers to find is Earth’s sister planet, bright Venus, which, like Earth, is about 8,000 miles wide. Even though Venus now appears as the wisp of crescent through a telescope it shines brilliantly as the Evening Star low in the southwest before it chases the Sun over the horizon.

Far more difficult to find is 30,000-mile-wide Uranus, the dimmest of the naked-eye planets. It too is in the southwest just after sunset, in the constellation Aquarius, but unless you know exactly where to look you’ll likely miss it. You’ll also need a very dark viewing spot well away from city lights.

While Uranus, the father of the Titans, can be seen without optical aid, your best bet is to look for him with binoculars on the night of Tuesday, Jan. 3, when he’ll be just a degree or so northwest of the new moon. His methane-rich atmosphere will make him look like a bluish star.

Far easier to find is bright and ruddy, 4,000-mile-wide Mars. The God of War sits high in the sky just after sundown, almost straight overhead. He’ll make his way slowly across the sky as the night moves on, finally setting in the early morning hours.

Mars will remain a prominent feature of the night for many month yet, not passing from the sky until spring turns to summer.

Just now making his move into the evening sky is golden Saturn, the 74,000-mile-wide ringed planet. He rises about 8 p.m. in the constellation Cancer and takes the entire night to cross the sky, setting in the hour after dawn.

West of Saturn is a ghostly naked-eye star cluster known as the Beehive.

Rising at about 3 a.m. is 88,000-mile-wide Jupiter, King of the Gods. This bright gas giant planet with its bands of red and swirling storms is directly southwest as dawn begins.

Minutes before the Sun rises the last of the naked-eye planets appears. Swift 3,000-mile-wide Mercury hovers just above the horizon as the sky begins to brighten, heralding the return of daylight. By the end of the week fleet-footed Mercury will be impossible to find as it fades back into the glare of the Sun.

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This column appeared originally in the Visalia (Calif.) Times-Delta on Dec. 22, 2005.

A Story in the Stars

A Story in the Stars
by Dave Adalian

High in the northern sky this time of year hangs the bright constellation Cassiopeia, the Seated Queen, and with her a tale of love, vanity, monsters and heroism that is as old as western civilization.

Vain Cassiopeia ruled ancient Aethiopia with her husband, King Cepheus. She was indeed lovely and bragged she was even more beautiful than the Nereids, companions of the sea god Poseidon. As punishment, Poseidon sent a terrible monster, Cetus, to wreak his vengeance upon the land.

King Cepheus consulted the oracle for a divine solution and was told he must sacrifice his daughter Andromeda to Poseidon to end the terror. So, at the king’s orders Andromeda was chained to the rocks at the edge of sea to die.

But death did not come to the maiden.

The hero Perseus was returning home after slaying Medusa, whose snake-haired head could turn men to stone. Flying through the sky on the winged sandals of Hermes, god of the underworld, Perseus spied Andromeda below and instantly fell in love. He swooped to her rescue and slew Cetus, saving both the girl and her land.

With Aethiopia secure, all was well, except for Cassiopeia. As punishment for her vanity and the trouble it caused she was doomed by the gods to ride forever in circles about the North Star, spending half the year dangling in embarrassment from her throne.

Cassiopeia’s bright stars form an obvious W-shape during warmer months. But on the longer nights of fall and winter the queen sits upside down, tied in her chair to keep from falling, and the W becomes an M above the North Star at about 8 p.m.

Cepheus’ faint constellation lies between the North Star and Cassiopeia, and Cetus, another dim group, is opposite Cepheus in the sky, far south with only a single bright star, Diphda.

Andromeda’s constellation and the bright and misty naked-eye galaxy that bears her name sit directly overhead around 8 o’clock during autumn nights. Perhaps her galaxy reminded the ancients of spindrift blown up from the waves that crashed around her feet as she awaited her terrible fate.

Perseus, holding Medusa’s head, is a starry constellation east of Cassiopeia. Medusa was also mother of Pegasus the winged horse, and his constellation and its Great Square shine west of Andromeda. West of Pegasus is the tiny Equuleus the Horse, which some say shows Chrysaor, earthbound brother of the flying horse.

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This column appeared originally in the Visalia (Calif.) Times-Delta on Nov. 24, 2005.

Real Deal on Mars

Real Deal on Mars
by Dave Adalian

If you were hoping to see Mars appear the size of a full moon last August, as a widely circulated hoax email suggested it would, no doubt you were very much disappointed.

Some prankster decided for reasons known only to himself to twist information about the close pass of Mars back in 2003 to make it sound as though the Red Planet would make an impossibly close pass by Earth this summer.

Thankfully, it didn’t happen. Had Mars come close as that hoax email described, the resulting disruption to Earth would have spelled disaster.

The real facts are these: Back in August 2003, Mars came closer to Earth than it has during recorded human history, about 34.6 million miles. For those lucky enough to get a look at the God of War through a telescope at 100X magnification during that close approach, its disk appeared the same relative size as a full moon does when viewed with the naked eye.

As I said in this space during summer of 2003, in a scope Mars looked like a pea in a Petri dish, although a beautiful one with reddish planes, dark surface features and clouds obscuring the southern pole -- in other words, like an alien planet that we still cannot be sure doesn’t harbor life of some kind.

If you missed it during summer 2003, it won’t be as close again until 2287. It really was a once-in-a-lifetime experience and a spectacular one at that.

But life is as full of second chances as it is once-in-a-lifetime opportunities.

Mars is coming in for another close pass this month, one of 40.3 million miles, a mere 4.3 million miles further away than in 2003. Bumping up the magnification to about 125X will give that full-moon effect once more. And, yes, it will be a breathtaking sight to behold.

Opposition, when Mars rises at sunset, will happen on Nov. 7, but the closest pass will come two nights before Halloween, when a pumpkin-colored Mars will rise about 6:30 to fly high in the east and come closest at about 8:25 p.m. It will be shining high and bright still when trick-o’-treaters take to the streets on Halloween.

Tonight, Mars is in the east over the trees by about 9 o’clock. If you watch night by night, you’ll see it rise earlier and double in brightness by October’s end as autumn’s warmth fails.

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Join the Tulare Astronomical Association Friday, Oct. 21, 8-10 p.m., for a close-up look at the Angry Red Planet at the Arthur L. Purcell Observatory, 9242 Ave. 184, 2.1 miles west of Highway 99. Information and directions: http://starry-starry-nights.blogspot.com/.

Clouds Win Again

Sorry, folks, but the satellite images show that this cloud cover over Central California is probably going to last most of the night, so there goes the star party. We'll try again on Friday, Oct. 21. See you then!

Return of the Long Nights

Return of the Long Nights
by Dave Adalian

Summer is taking an early departure this year, folding away her brown mantle and allowing the cool days and chill nights of autumn to come quickly as the leaves begin to fall.

This is fitting as (on Sept. 22, 2005) at 2:23 p.m. PDT the Sun crosses south of the celestial equator, reaching equinox and marking the moment when autumn begins and the days shorten while nights grow long and cold.

When the Sun sets this evening, it will fall directly west and rise again tomorrow due east, silhouetting the crags of the Sierra Nevada. Though the periods of light and dark won’t be perfectly equal as the Latin term equinox implies, the time between sunset tonight when half the Sun’s disk is below the horizon and sunrise tomorrow when half the disk is above the horizon will be just eight minutes shy of 12 hours.

The equinox is the moment when the Sun crosses the dividing line that splits the sky into two equal northern and southern halves, creating some special effects here on Earth.

At the equator on the days of the March and September equinoxes, the Sun not only rises and sets at the points of true east and west, it also passes directly overhead when it reaches its highest point in the sky, something it never does at more northern or southern latitudes.

At the poles, the effect is far more dramatic.

At the North Pole, the September equinox signals a plunge into six months of darkness, with the Sun dropping below the horizon not to be seen again until the end of March.

On the bottom of the planet, the effect is reversed, with the Sun finally returning to the sky for six uninterrupted months of daylight. Instead of rising and falling as it does elsewhere, during the months-long period of day the Sun skims along the icy horizon, climbing higher in the sky as the solstice approaches.

Were it not for the killing cold of the arctic winter, the North Pole would be a Moon-lover’s delight. During the six-month darkness, the Moon rises above the horizon not to set again for two weeks. The Moon moves through its cycle in unashamed plain sight before dipping again below the horizon for a fortnight’s absence.

Late Sept. 21 and 22 here at home, the Moon will put on a beautiful display in the east, joining the Seven Sisters of the Pleiades, the V-shape of the Hyades and a bright and ruddy Mars.

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Join the Tulare Astronomical Association for a public star party this Friday, Sept. 23, 8:30-10:30 p.m. at the Arthur L. Purcell Observatory, 9242 Ave. 184, south of Tulare and 2.1 miles west of Highway 198.

Deep Impact Reveals Comet's Secrets

The first findings from the Deep Impact collision with Comet Tempel 1 back in early July have been announced and the mission's results are going to change the way astronomers think about comets in a lot of ways. We've assumed comets were dirty snowballs, but it's looking more like they're icy dirt balls made mostly of powder and have the consistency of a soufflé, so don't slam the oven door or your comet may collapse.

Here's a great article on the findings from Science News.

Soak In Some Earthshine

When a very slim crescent moon joins Jupiter, Venus and Spica on the western horizon tonight just after sunset, be sure to look for the Earthshine, too.

The Sun is the only source of bright light in our solar system. All the light coming from the planets and their moons is just a reflection of our home star. When the Moon is only a couple of days past its new phase it presents a large dark limb, and the light that makes that dark limb visible is Earthshine, light from the Sun that strikes the Earth, reflects back to the dark portion of the Moon and then shines back on the Earth.

Venus and the Virgin

The sky show continues tonight on the western horizon after sunset with Spica, the alpha star of Virgo the Virgin, shining less than two degrees southwest (down and to the left) of Venus. Jupiter is about four degrees to the right. For those with a clear view to the west, a very young new moon is just above the horizon and will set by about a quarter after 8 o'clock local time. The Moon will be right in the midst of this grouping tomorrow night 30-45 minutes after the Sun goes down.

One Hundred Billion Failed Stars

For every star shining in our galaxy there's another one that didn't make it. Astronomers at Arizona State University working from Hubble Space Telescope infrared data have discovered the Milky Way has as many brown dwarf bodies as it does stars -- 100,000,000,000 of them and every one without enough mass to begin nuclear fusion, the process that makes the stars shine. These dark bodies weigh anywhere between 13 to 75 times as much as Jupiter, so their combined mass isn't enough to account for all of the galaxy's so-called missing matter by a long shot.

Here's Astronomy.com's article announcing the discovery.

Look to the West

Don't forget the meeting of Jupiter and Venus. Look due west 30 minutes after sundown to see these bright planets converge. They'll come closest to one another Thursday, Sept. 1, when they'll be about 1.2 degrees apart, just more than twice the width of a full moon or about the width of your pinkie finger when held at arm's length.

Click here for my earlier, more detailed post about this conjunction.