Tuesday, December 16, 2003

Return of the Rings

Return of the Rings
by Dave Adalian

Somewhere in the cold and empty void beyond the orbit of Jupiter a spacecraft is racing toward a long-awaited rendezvous.

Seven years ago NASA and the European Space Agency’s Cassini-Huygens Mission to Saturn left Earth. Twice it swung past Venus, once returned by Earth, and finally it flew past Jupiter on the way to its destination. Cassini is scheduled to enter orbit around the ringed gas-giant planet on July 1 of next year.

When the probe arrives, it will transmit back to Earth new information about the ringed world and its largest moon, Titan. Titan is the only moon in the Solar System with a thick, planet-like atmosphere, and the Huygens portion of the probe will drop below it to the surface to see for the first time what lies underneath. Perhaps lakes or oceans of liquid methane.

Potentially glorious pictures of Saturn’s 150,000-mile wide rings, its stormy atmosphere and the other lesser moons will also be captured by Cassini--the most complicated robotic probe mankind has built.

As intellectually stimulating, scientifically important and just plain exciting as that is, all the images and data in the world don’t rival viewing Saturn with one’s own eyes as it moves through the night. Now through March is the best time for doing just that.

Saturn seems to know 2004 is its year, and is planning a New Year’s celebration. Like Mars before it last August, Saturn is coming to opposition--the time of year when it appears to be opposite the Sun in the sky and is closest to Earth--on New Year’s Eve.

Because it is at opposition, Saturn rises on Dec. 31 as the Sun sets, around 4:45 p.m.

By 9 o’clock it is well up in the east, shining bright yellow from its perch in the zodiacal constellation Gemini. To Saturn’s left are the twin stars Castor and, slightly east, Pollux.

As the year turns at midnight, Saturn appears to be on the imaginary meridian line joining north pole to south, signaling our longitude--119 degrees west--is at its closest to the ringed planet for this pass. Saturn is about 800 million miles away.

This view is made truly spectacular by the current angle of Saturn’s rings, almost completely open toward Earth. A telescope will show the rings and perhaps details within them. If you haven’t got a telescope, find someone who does. It’s worth the effort.


This column originally appeared in the Visalia (Calif.) Times-Delta on Dec. 16, 2003.

Tuesday, November 18, 2003

Generous Skies All through November

Generous Skies All through November
by Dave Adalian

November is a traditional time of plenty on Earth, and this month the generosity extends itself into the skies.

As I mentioned last month, Venus has retaken her place as the Evening Star for the holidays, becoming the brightest of the visible planets as the year dwindles. This week, she sits low--almost due southwest at sunset--shining bright but sinking fast.

The Evenstar will be easier to spot on Tuesday, Nov. 25, when a brand new crescent Moon, just a sliver really, sits to her left. It will take a keen eye to spot so slim a Moon. Those who do may notice how bright the normally dark part of the Moon seems. That’s earthshine reflecting back at us from the shaded lunar surface.

During the last days of November, Venus follows another bright planet, swift Mercury, into the gloaming. Mercury is called quick with good reason; if you don’t get a look at him in early December, he’s lost in twilight by mid-month. For those two weeks, he’ll be below and to the right of ever brightening Venus.

While waiting for Mercury to make an appearance, take time to revisit a now much weakened Mars. The Warrior God is only about one-tenth as bright as at his height three months ago. High in the southeast at dusk, Mars sets not long after midnight. Luna will visit him on Nov. 30 and Dec. 1.

By about 10 o’clock, Saturn is high in the east among the bright stars of Gemini. Like Mars before him, Saturn is gathering for a close pass by Earth on New Year’s Eve. He still shows few obvious signs to distinguish him from a star. Best to let the Moon point Saturn out when she sits directly above him on the night of Dec. 9, then to his left on Dec. 10.

With Saturn’s rings still open and reflecting sunlight in our direction, the Bringer of Death with its dirty yellow glow is a bright and stunning sight through the telescope. See it this month or next as it won’t be this spectacular again until 2030.

The King of Planets is still better for morning larks than night owls as winter approaches. Although it rises now not long after midnight, it isn’t until the last hour or two before dawn Jupiter is best. The Moon marks Jupiter and the constellation Leo in the early morning Dec. 16.

Clear skies!


This column originally appeared in the Visalia (Calif.) Times-Delta on Nov. 18, 2003.

Tuesday, October 21, 2003

Tricks and Treats in the Sky

Tricks and Treats in the Sky
by Dave Adalian

When little witches, ghosts and evil things that tarry in dark places go abroad this Hallowe’en, treats better than those in plastic wrappers await trick-o-treaters who turn their eyes skyward.

If they can find a clear view west as they go from door to door, those who come out early on Oct. 31--just a few minutes after sundown--might catch a view of Venus shining low on the horizon as the Evening Star.

Venus climbs higher off the horizon each night during autumn, reaching its highest point near winter’s end then sinking back into the west in spring. Look for Mercury to join Venus in time for Christmas.

A Moon only a few hours shy of first quarter will be due south at sunset on the last day of this month, haunting the dim, V-shaped constellation Capricornus, the Sea Goat. East of the Moon, a lingering Mars holds only about half the luster it showed back in August. Still, it shines brighter now than everything else but the Moon.

Moving east and growing larger night-by-night, the Moon passes Mars on Nov. 2-3 and slips into Aquarius, the Water Bearer, another indistinct and sprawling constellation of the fall Zodiac. The only bright star there is Fomalhaut (FOAM-A-LOW), appearing yellowish-white near the horizon below Mars.

The Moon grows to full the night of Nov. 8, but when it comes up that evening it might not be there to be seen. The second total lunar eclipse of 2003 begins at 3:23 p.m. that Saturday, well before the Moon rises here in the West. But, totality, when the entire disk of the Moon is shrouded by the darkest part of Earth’s shadow, doesn’t happen until 5:06 p.m., just as the Moon is rising here.

For the first half hour of its journey across the sky, the Moon will be hidden. Eclipsed moons are notorious for their strange colors. Last May’s seemed to be pale and washed out. How will this one compare? Perhaps orange or bloody red or something more like the color of fading Mars.

Pay attention to the shape of the Earth’s shadow as the Moon emerges, beginning around 5:31 p.m. Though fuzzy at the edges, Earth’s shadow is distinctly round, proof positive if you need it we live on a sphere.

By 8:15, October’s Frost Moon will be shining bright again during the rest of a long autumn night.

Clear skies.


This column originally appeared in the Visalia (Calif.) Times-Delta on Oct. 21, 2003.

Tuesday, September 23, 2003

Mars Didn't Fall Short

Mars Didn't Fall Short
by Dave Adalian

As the whole world watched last month, Mars swung closer to Earth than ever in recorded history. It was quite the event.

Observatories all over were awash in a sea of visitors eager for a glimpse of the Red Planet as it passed. The Purcell Observatory in Tulare was certainly no exception, as record numbers turned up for a gander through the telescopes.

Mars didn’t disappoint. It might even have been showing off some. I’ve certainly never seen it look better. Neither has anyone else.

Unfortunately, those who didn’t see Mars at its absolute best in August won’t get another chance for 284 years.

Good news though: The 2003 show isn’t over!

Mars is still looking very good. A peek at it through a telescope this week won’t be rivaled until 2018. Members of the Tulare Astronomical Association will host a public star party Sept. 26, free of charge as always.

Those who don’t have a scope and can’t make the party should try taking in the many sights that need no optics during this season of summer’s retreat.

Mars is still a naked-eye beauty, already riding high in the southeast as the Sun sets. As the days pass and Mars moves away, watch carefully to notice its yellow-red glow grow dimmer night by night. On the nights of Oct. 5 and 6, it will be joined by the nearly full Hunters Moon.
After sunset at this time of year is when three bright stars--Vega, Deneb and Altair--sit straight overhead at the top of the sky. These stars form the Summer Triangle, a figure which surrounds a bright patch of Milky Way glow visible from here in town when the neighbors’ lights are low and the Moon is down.

Around an hour before midnight and earlier each night, the Seven Sisters of the Pleiades sparkle to the east. To see more than six of these young, hot blue-white stars in Taurus will require a trip into the countryside.

By midnight the first stars of Orion the Hunter rise in the east, and by 2 a.m. the familiar winter constellation is well above the horizon. To the left of Orion’s famous red star Betelgeuse is another bright point of light, one that unlike other stars doesn’t twinkle. This is Saturn.
Watch Saturn rise earlier and climb higher as the fall nights grow longer and the cold begins to linger.

Clear skies.


This column originally appeared in the Visalia (Calif.) Times-Delta on Sept. 23, 2003.

Tuesday, August 26, 2003

Mars Makes Close Approach

Mars Makes Close Approach
by Dave Adalian

When practicing a hobby like astronomy once-in-a-lifetime events happen all the time. But, three hours after midnight tonight is a very big event indeed.

At 2:51 a.m. on August 27, Mars will be closer to Earth than during all of recorded human history.

While experts disagree on when Mars was last this close, all estimates put the number at longer than people have been keeping track of things like this or anything else. Reliable numbers put the date at 60,000 years, give or take a long weekend.

In any event, this is a really exciting time for stargazers of all level. Unfortunately, Mars Fever doesn’t seem to be spreading as it should. Maybe it’s because those in the know tend to call big events like this by silly names. We call this one an opposition.

Earth and Mars are like runners on a track, with Earth on the inside lane. About every two years we pass Mars by, and because the orbits aren’t perfect circles, we pass closer at some times than at others. This go-round, the Red Planet will be a scant 34.6 million miles away.

These close passes coincide with Mars’ opposition, the time when the Sun, Earth and Mars align, and Mars sits opposite the Sun in the sky. What makes the 2003 opposition a truly big deal is Mars will be bigger and brighter than any living observer has ever seen it.

To see Mars at its finest, step outside an hour or two after sunset tonight and look a little south of due east. Mars will be unmistakable, shining as the brightest and reddest “star” in the sky.
As an added bonus, on Monday, Sept. 8, Mars will be joined closely in the sky by a nearly full Moon. Any pair of binoculars will really enhance the view.

Of course, the best look at the Red Planet will be in a telescope, but even then don’t expect exactly Hubble-like views. At 100X magnification, Mars will seem like a pea in a petri dish even though it will have the same apparent size as the full Moon when seen unaided. Even so, details like the polar ice caps, clouds and dark regions on and over Mars ruddy surface will be awesomely clear, especially when conditions allow for much higher magnifications.

One way or another, take a look at Mars sometime this week. Those who miss out will never get another opportunity like this one.


This column originally appeared in the Visalia (Calif.) Times-Delta on August 26, 2003.

Tuesday, July 22, 2003

Moon May Outshine Meteor Shower

Moon May Outshine Meteor Shower
by Dave Adalian

Some say a full Moon is the most romantic nighttime sight. Others say it’s shooting stars. In mid-August we’ll get both on one night during the Perseids (per-SEE-ids), the year’s most reliable meteor shower.

Falling stars aren’t really stars. Your run-of-the-mill meteor is caused by a tiny piece of rock--a meteoroid--the size of a grain of sand with the consistency of ash. They vaporize high in the atmosphere as friction from their tremendous speed causes them and the air around them glow briefly and brightly.

Most of the time they arrive sporadically, a couple every hour more or less. Periodically the rates climb, putting on a spectacular show if conditions are right.

The random bits of debris are crumbs from ancient collisions among comets and asteroids. Left floating for billions of years, the pieces sometimes fall to Earth in blazing glory one at a time.
Meteor showers, however, are caused by Earth crossing the path of a large comet or asteroid. As these bodies loop around the Sun, they lose pieces of themselves which slowly drift ahead and behind until they spread throughout their parent’s orbit.

When Earth enters one of these streams and turns its night side toward the onrushing meteoroids, the fireworks begin.

On the night of August 12, we’ll be in the thickest part of the trail left by Comet Swift-Tuttle. When this happens, rates usually climb to 80 meteors or more an hour. In 1993, hourly rates at the peak were estimated at 200 to 500.

Unfortunately, August 12 is also the night of full Moon and our bright neighbor will outshine most of the show.

It’s still worth going out for a look. The Moon will be low when the shower peaks near 10 o’clock, so from a dark site we might see 20 to 40 meteors or more an hour. Or perhaps less or even none--meteor shower prediction is still a science in its infancy. But, surprises do happen.
To view the shower, set up a low-slung chair or lounge with your head pointing northwest--the opposite direction from a close pairing of the rising full Moon and bright orange Mars--and watch the skies overhead.

The Perseids’ radiant, the area where the meteors seem to come from, lies north in the constellation Perseus. The shower lasts from July 23 to August 22, with slightly increased meteor activity before and after the peak.

Clear skies!


This column originally appeared in the Visalia (Calif.) Times-Delta on July 22, 2003.

Tuesday, June 24, 2003

Think About Light Speed

Think About Light Speed
by Dave Adalian

My birthday is in July, making this a perfect time to talk about cosmic distances and the speed of light.

Make sense?

It does if you realize somewhere out there is a star as many light years away from Earth as I am years old.

While I’ve been living my life, going to school, working, getting married and having children, light from my birthday star been streaming across the universe at, well, light speed, of course. Light speed is the fastest anything can go, as far as we can tell, about 186,000 miles every second--more than seven trips around Earth’s equator every time your heart beats.

How far will the light from my birthday star have come to get to me?

For perspective, remember the Moon averages a distance from Earth of about one and a half light seconds.

It took our space ships four days each way to close that meager gap.

The Sun, at an average distance of 93 million miles away, is only eight minutes distant at the speed of light.

The furthest planet out from the Sun, Pluto, is only a scant five and a quarter light hours from us. The Voyager probes, the fastest man-made objects there are, passed that distance in about 12 years.

Far beyond that, marking the distant edge of the Solar System, is the Oort Cloud, a sphere of comets surrounding our sun at a distance of about one and a half light years, or somewhere in the neighborhood of nine trillion miles.

The Voyager probes will need about 40,000 years to get there.

Light from my birthday star will have come the better part of 214 trillion miles, and it’ll hit us just as I finish my 36th trip around the Sun--a nifty coincidence making the occasion seem more grandiose.

This year, my birthday star is 54 Piscium--a dim star in the constellation Pieces. I could have searched one of several lists of stars available in books and online to find it, but instead I used a clever little program at the Joint Astronomy Centre.
If you let the Centre do the work, you’ll also get a map of the sky you can use to find your birthday star. If you have trouble finding your star, I or one of my fellow amateur astronomers would be happy to help at the Tulare Astronomy Association’s monthly star parties.

Clear skies!


This column originally appeared in the Visalia (Calif.) Times-Delta on June 24, 2003.

Tuesday, May 27, 2003

Strange Lights on Summer Nights

Strange Lights on Summer Nights
by Dave Adalian

Summer is my favorite time of year. Nights are warm, and the starry sky is full of wandering lights--mysterious beacons in the sky. X-Files stuff.

OK, so these aren’t aliens coming to meet and eat mankind. But they are spacecraft. And they are watching us. The guys at the controls, though, are here on Earth and as human as you and me.

Until 1957, Earth had only one satellite, the Moon. In that year the Soviet Union launched Sputnik and since then some 27,000 manmade objects have been cataloged in the sky. About 9,000 or so are still in orbit, and a few hundred of them can be viewed with the naked eye.
This is the best time of year to see them. Earth’s seasons are caused by our planet’s tilt. When our hemisphere leans toward the Sun, the weather warms into summer. This slant makes Earth’s shadow fall low in the sky a few hours after sunset and before sunrise, leaving satellites exposed to the light and easy to see.

The only thing you need for satellite hunting is a dark, clear, moon-less sky like those we’ll have this weekend. The darker the sky, the better the hunting, but around here the backyard will do fine. What I like to do is lie back--in the swimming pool if it’s warm enough--let my eyes adjust to the dark, then wait until I see a star that’s come loose from its moorings drifting slowly across the sky before fading into Earth’s shadow. This time of year, I can easily catch a dozen or more roving lights before midnight, when Earth’s shadow grows tall.

Mostly, the lights are dim but steady points, like stars sailing slowly across the night. But, some are different. Iridium satellites, a group of communication repeaters, can flare up unexpectedly, quickly becoming the brightest thing in the sky before disappearing just as fast. Others flash on and off as they tumble through the sky. Mostly, these are old, dead machines falling uncontrolled through space.

One of the brightest satellites is the International Space Station. It appears regularly over the Valley, and you can find a schedule of its passes--and the passes of dozens of other manmade moons--at Heavens-Above.com. There you’ll find maps, instructions on how to use them and some details about what you’re seeing. You can also use the service to look up previous sightings.

Happy hunting!


This column originally appeared in the Visalia (Calif.) Times-Delta on May 27, 2003.

Tuesday, April 29, 2003

Earth Will Eclipse the Moon on May 15 (2003)

Earth Will Eclipse the Moon on May 15 (2003)
by Dave Adalian

When the Moon comes up on the evening of May 15, it will be slipping into the shadow of Earth and a total lunar eclipse. There will be plenty to see and much to learn before it returns to normal just three hours later.

Every 30 days, Earth, the Moon and the Sun describe a line in space, and from Earth we see this as a full moon. Now and then, they align just so and for a few hours Earth upstages Luna, blocking its Sun. Although this is fairly rare, it will happen twice this year for us: May 15 and November 9. Of the two, May’s will probably be the better show.

The Moon rises at 7:40 p.m., but the Sierra will block our view for a few minutes. When the disk of the Moon shows itself, it will already be in the shadow’s lighter outer edge, the penumbra, and well into its darker center, the umbra. You won’t really notice much difference in brightness caused by the penumbral shadow, but the difference caused by the umbra will be striking--a blurry-edged curved line moving on the face of the Moon.

The umbra will continue to creep across until by 8:14 p.m. the entire face is covered. This is totality. The Moon inside the umbra looked dark when some part of the surface remained lighted. Now, it glows an eerie coppery crimson. The orange color reflected back during totality is red light passing through Earth’s atmosphere and bending into the path of Earth’s shadow. Sunlight is comprised of all different colors, and when it passes through Earth’s atmosphere the blue light is scattered. This is what makes the sky blue and the rising full moon bloody. If you could stand on the Moon during an eclipse, the effect would make Earth look like an absolutely black disk floating in a ring of fire.

While the Moon is dark is the time to look at the stars around it. The night of the eclipse, Luna is riding between the claws of Scorpius the Scorpion. Just below it is the head of the scorpion, and just below that is the red star Antares, a name that means rival of Mars. The scorpion’s tail is below the horizon during the eclipse, but will show itself as the Moon rises.

The height of totality comes at 8:40 p.m., and the Moon will start to move out of the umbra by 9:07 p.m. As it goes, take another look at the curved line of shadow. What you’re seeing is evidence the Earth is round, as the only spinning object that can cast a shadow like that is a sphere.

At 10:13 p.m., the Moon will have moved out of the umbra, and in another hour, as Luna passes out of shadow to become her familiar self again, the show will be over until autumn.


This column first appeared in the Visalia (Calif.) Times-Delta on April 29, 2003.

Tuesday, April 01, 2003

Follow Rising Mercury in April

Follow Rising Mercury in April
by Dave Adalian

Most of us enjoy gazing at the night sky, but only a lucky few see the stars and planets as more than just a scattering of pretty lights. That’s too bad, because once you know what you’re looking at, the sky at night is an even more fantastic and wonderful place.

Fortunately for us, all during April finding our way through the starry night is easy as following the Moon.

First stop on the lunar tour is the most challenging. On April 3 around 7 o’clock, a sliver of moon will hang low in the west. Below it and to the right, see if you can find Mercury above the treetops, looking like a star with an orange tint. Mercury is climbing toward its highest point, reaching it the evening of April 16. By finding it early, the winged messenger will be easy to follow, rising higher each evening then slowly settling back into twilight my month’s end.

Meanwhile the Moon moves on, until April 5 it sits left of the Pleiades, a bright star cluster 380 light years away. On April 7, the Moon is above another bright light, dark yellow Saturn. Every dozen years, Saturn’s rings open wide as they go, and now is one of those times. The best way to see them is through a telescope, and if you don’t have one the Tulare Astronomical Association will be glad to share the view at a star party Friday, April 4, starting at dusk. Local stargazers meet at the Arthur Purcell Observatory, 9242 Avenue 184, south of Tulare and two miles west of Highway 99.

The night of April 9, the Moon will be near two bright stars--Castor and Pollux, the twins of Gemini. By April 10, the Moon will be next to the brightest point of light now in the night sky, Jupiter. This is a great chance to share the night with kids and test their eyesight. Some sharp young eyes can actually see the moons of Jupiter without help.

To catch the final two planets on the lunar tour wait until the end of the month and get up early. Look east on April 23 before dawn, and find the moon below and to the left of Mars, the Red Planet. Then, before dawn on April 27, Luna ends our tour at a spot left of Venus, the brilliant white Morning Star.

Enjoy the ride.


This column, the first in the Starry Nights series, first appeared in the Visalia (Calif.) Times-Delta on April 1, 2003.