Skywatch March 2005

Skywatch Line for Friday, March 4, through Sunday, March 6, 2005 By Alan French

Mercury, being close to the Sun, never appears high in the night sky and only makes brief appearances just after sunset or just before sunrise.

Although it is bright enough to spot easily, you need good timing and clear skies down to the horizon to catch this rather elusive planet.  Although it is one of the five naked eye planets, many people have never seen Mercury.

Mercury is now making a nice appearance in our evening skies, and you'll have a good chance to become one of the people who have seen Mercury.  Why not share it with your friends and family?

 The Sun sets around 5:50 PM over the weekend, and you'll want to look for Mercury an hour later – at 6:50 PM.  For a chance to spot Mercury, you'll need to find a place with a good view of the western horizon, and you'll have to hope for an evening where the western horizon is free of clouds.

Although Mercury is bright enough to see with the unaided eye, a pair of binoculars will improve your chances of a successful hunt, especially if the horizon skies are a bit hazy.  Once you've found it in binoculars, you can try spotting it with the eye alone – and knowing exactly where to look will improve your chances.  If you don't own binoculars, don't despair, Mercury is bright enough to spot with the unaided eye, and if the sky conditions are right, it should be obvious with your eye alone just above the western horizon.

 The planet will be due west, and will be a mere five degrees above the

horizon at 6:50 PM.  Keeping in mind that a fist held at arms length spans 10 degrees across the knuckles, you can see why it is important to have a good horizon to the west, and clear skies there.  If you saw where the Sun went down, look for Mercury five degrees to the north, or right, of where the Sun set.  If you scan the western horizon with binoculars, putting the bottom of the field of view just above the horizon, you'll have a very good chance of spotting the fairly bright starlight point of light that is Mercury.  Nothing else in that area of the sky will be as bright.

 Mercury will become fainter as the days go by, but it is also moving higher in the evening sky, so it should remain easy to spot for the next two weeks. Next Friday a young, crescent Moon will be near the planet, providing a nice guidepost.  Next Saturday, March 12, the planet will reach its highest point in the evening sky.

Skywatch Line for Friday, March 18, through Sunday, March 20, 2005 by Alan French

This Sunday marks the vernal equinox – the first day of spring here in the northern hemisphere.  Spring will begin for us at 7:33 PM.  On the vernal equinox, the Sun lies in the Earth's equatorial plane.  At this time of year, the Sun rises in the east and sets in the west, and is overhead at Noon for people on the equator.  Back on the winter solstice, the Sun rose well toward the southeast and set well toward the southwest, and our days were shortest.  When we reach the summer solstice on June 21, the Sun will rise considerably toward the northeast and set well toward the northwest, and our days will be longest.  As we are now moving toward the summer solstice the days are lengthening and our dark skies fill less of the night.

 The Sun now rises around 6:01 AM and sets around 6:07 PM.  The Moon was at first quarter on Thursday, so more than half the night is dominated by a bright, waxing gibbous Moon.  Over the weekend the Moon will move through the constellation of Gemini, passing near the bright star Castor, and not too far from Saturn on Friday and Saturday nights.

If you look toward the south on Friday night at 7:00 PM, you will find the Moon high in the sky.  The bright star to the Moon's lower left, about ten degrees away, is the planet Saturn.  Above and to the left of Saturn you will see the bright star Castor.  If you look again at 9:00 PM, you will find that the Earth's rotation has shifted the sky westward, and Saturn and the Moon will be more toward the southwest.

 If you look at the sky again on Saturday night you will find that the

Moon's eastward has shifted its position considerably, and it will be closer to Saturn and considerably closer to Castor.

At 7:00 PM, the Moon will now be to the upper left of Saturn and a bit less than six degrees away.  Castor will be almost directly above the Moon and less than two degrees away.  If you look again on Sunday night, you will find the Moon has now moved far enough eastward to have left the constellation Gemini behind, and the Moon will now be in less conspicuous Cancer.

 If you own any type of telescope, take time to point it toward Saturn.  The rings are visible in almost any telescope having a magnification of at least 30.  Always start with your lowest power.  The wider field makes it easier to aim your telescope, and the lowest powers may provide the sharpest looking view.

This is the Skywatch Line for Monday, March 21, written by Joe Slomka.

The Sun sets tonight at 6:09; night falls at 7:44 PM. Dawn breaks at 4:20 AM, and ends with sunrise at 5:55.

At sunset, the Moon shines brightly due South. As the sky darkens, Saturn also glows high in the southern sky. Saturn is one of the few objects that can shine through the nearby nearly full Moon. The Cassini space mission continues to reveal new mysteries. Saturn’s moon, Enceladus, is only a couple of hundred miles in diameter. Recently, Cassini’s instruments detected an atmosphere. The problem is that most planetary scientists think Enceladus too small to hold onto an atmosphere. As is the case with most scientific ventures, results only inspire more questions and more study.

By twilight’s end, Jupiter has already risen. It is usually best to wait a few hours for Jupiter to become higher before studying it in detail. While Saturn’s moons require telescopes, Jupiter’s four moons can be seen in ordinary binoculars.

Comet Machholz continues to inhabit the sky around Polaris, the Pole Star. Telescope observers should find it about eight and half degrees in the direction of Draco’s tail.

First light finds Mars already up, to Sagittarius’ east. The Red Planet slowly grows brighter and bigger, preparing for a good Fall show. Mars has weather. For centuries observers have seen dust storms. However, a week ago, Spirit encountered a dust devil, a mini-tornado. Dust devils are common in desert-like climates. The same must apply to Mars. However, this dust devil actually swept clean Spirit’s solar panels of a year’s accumulated Mars dust. For the first time in a year, Spirit’s batteries are fully charged. Again, Mars likes to surprise us.

Two giant constellations occupy the night sky, Ursa Major (the Big Dipper) and Orion. Unlike most constellations, these two are actually groups of stars sharing a common motion. The middle stars of the Dipper form an association about eighty light years away. Orion’s stars also are a true group that share a common motion and occupy an arm of our Milky Way galaxy about 1000 light years distant.

Clear Skies

Joe Slomka

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