Heads UP! for March 2011

Evening’s Bright Dot is Jupiter, Which Leads Us to Mercury
The Moon Runs Over a Star
March Comes in Like a Lion – Leo Rises
The Space Station and Solar Sail Make Appearances
Where are Saturn, Venus and Mars?
Don’t Forget Daylight-time Starts March 13th
Which Planet is Closest to Us?

Watch that bright dot in the western sky right after the sky gets dark in the evening. That’s the planet Jupiter. It will get lower in the sky every night, but as it gets down, it will pass the planet Mercury from the 13th through the 16th. If you have never seen Mercury in the sky, this is a great opportunity to see it. Mercury will be dimmer than Jupiter, but easy to see without optical aid with Jupiter nearby pointing the way.

Look out for the Moon this month as it cruises though our skies. On the 1st and the 31st, it lines up with Venus in the morning sky just before sunrise. It shares the evening twilight with Jupiter on the 6th and 7th. And the first quarter moon, when the moon looks half-full, is stuck high in the horns of Taurus the bull on the 12th. If you want to take up a challenge with your binoculars or telescope, the sight of a star instantly winking out when the dark limb of the Moon passes in front of it is exciting and educational (showing the lack of a substantial atmosphere on the Moon). The Moon covers μ Geminorum, a star normally easily seen without optical aid (magnitude 2.9) at the foot of one of the Gemini twins, on the evening of the 13th about 7:00pm in the New York City area. The moon’s glare may make it hard to find the star, so find the moon high up in bright twilight sky in advance of 7pm and look to the left of the moon with your optical aid to see the star. Then wait and watch for the moon to run it over.

Does March come in like a lion? Is our skies, it does, as Leo the lion rises into our evening skies from the eastern horizon. The bright winter constellations we have been enjoying seem to move quickly westward, as if in fear of our not-cowardly lion of the east.

Saturn is an object for late evening object through early morning. At 800 million miles away, it is tiny, but in a telescope, unmistakably Saturn with its ring. In your telescope, you’ll also see a nearby star. Saturn’s largest moon, Titan is fainter, but visible in telescopes larger than 3 inches wide.

Venus is still out there in the pre-dawn sky, only about one fist-width or so above the horizon.

Mars is still hiding in the glare of the Sun, but it is far enough from solar conjunction that scientists are listening again for signals from the Spirit rover, which hasn’t been heard from since the beginning of its Martian winter last March. The Opportunity rover is trundling along toward the large crater called Endeavour. Opportunity has been on Mars for 2511 Martian days and has 16½ miles on its odometer.

The International Space Station has bright evening-time overflights of our area now through the 13th and in the mornings starting on the 24th. The Nano-sail D solar sailing satellite has unfurled and NASA is having a contest to encourage photos of it as it travels across our skies like a moderately bright star. The best times for viewing Nano-sail D are in the evening through the 6th, and in the morning after that. Check spaceweather.com or heavens-above.com as the viewing times may change as the sail’s orbit is modified by solar wind pressure and bumps from the few atoms that make up our atmosphere at that altitude.

Remember that daylight time starts on March 13th, making the time of sunrise and sunset 6:59am and 7:07pm, respectively. Note that it’s not exactly a 12-hour period of daylight; one reason is due to the refraction of sunlight by Earth’s atmosphere from below the horizon lengthening daylight by a few minutes.

Which planet is closest to Earth most often? The surprising answer is Mercury. This year, for example, Mercury is the closest planet to Earth from March 14th through December 27th, when Mars becomes the closest planet to Earth. The distance from Earth to Venus is more than the distance from Earth to Mercury until January 7th, 2012, as Venus spends most of 2011 moving away from Earth in its slightly faster, inner orbit.


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