Archive for May, 2009

M57: The Ring Nebula

Tuesday, May 19th, 2009
M57

The constellation Lyra, in one corner of the famed “summer triangle”, is home to Messier 57, commonly known as the Ring Nebula. A classic example of a planetary nebula, M57 is not one of the larger or brighter Messier objects. However it is easy to find and, even through a small telescope, lives up to it’s “ring” name. To find M57, start with Vega – a very bright magnitude 0 star at the westernmost corner of the summer triangle. Trailing off to the east of Vega, the shape of the constellation Lyra can be faintly seen. Aim your telescope with a low

Lyra

power eyepiece about halfway between the two stars at the “bottom” of Lyra. M57 should be visible as a small ring near the center of your field of view. Switching to higher magnification can allow a closer look at the ring structure. Despite a dim magnitude of 8.8, M57 is easily visible and shows a surprising amount of detail, making it a worthy telescopic target. As is common for planetary nebulae, the distance to M57 is difficult to determine. Estimates have ranged from 1000 to 5000 light years, with a current best estimate of around 2300 light years.

Two for the Price of One

Saturday, May 16th, 2009

Why look at just one planet when you can see two? In the coming weeks there will be a pair of close planetary pairings. But  with both showing up in the predawn hours, you’ll have to get up early to see them. The most obvious pairing, easily visible to the naked eye, is Venus and Mars. Just start by finding Venus low in the east, now in the constellation Pisces. At a dazzling magnitude -2.9, it’ll stand out clearly. Slightly lower and to the left will be Mars, shining at magnitude 1.2. As time goes on the pairing will become even better, with the planets appearing higher in the sky, brighter and closer together.   They will reach their closest point on June 21. By then they will be in the constellation Aries and will be shining at magnitudes -3.5 and 1.1 respectively. 

Jupiter and Neptune

While Venus and Mars are putting on their show, another interesting pairing will be taking place in the constellation Capricorn. But without a telescope, you’ll only see half of this pairing. During the last week of May, Jupiter and Neptune will appear less than a degree apart. With Jupiter at a bright magnitude -2.5, it will stand out clearly in the southeastern sky, along the eastern edge of Capricorn. Look slightly above Jupiter for Neptune. If you’re using a low power eyepiece, they should both be visible in the same field of view. With Neptune at a dim magnitude 7.9, it won’t be the most spectacular pairing. But it’s always interesting when two planets appear so close, and it’s also a good chance to spot a planet that can sometimes be hard to find. The picture at right shows how the pairing would look on the morning of May 20. Star Mu Capricornus, at magnitude 5, will join the pair. The red circle indicates a typical field of view through a low power eyepiece. Although not shown in the picture, Jupiters large moons will add to the show and are always worth a look. So if you’re up early (or very late, as is the case for some of us) don’t miss this pair of planetary pairings.

Is That a Spaceship in the Sky?

Tuesday, May 12th, 2009

Have you ever gone outside at night and seen a spaceship flying overhead? If you’ve spent much time at all looking at the night sky, the answer is probably yes. Now I’m not talking about anything piloted by little green men. These spaceships are of a very Earthly origin. Although the space shuttle, on it’s mission to service the Hubble telescope, is in an orbit that won’t make it visible from North America, the next few days will be ideal for viewing the International Space Station (ISS). Visible as a point of light (brighter than magnitude -2 on some passes) moving at a quick but steady pace across the sky, seeing the ISS can add a bit of extra fun to a night of stargazing. Check out the Heavens Above website to find when the ISS will be visible from your location.

Rayed Crater Tycho

Sunday, May 10th, 2009
Tycho Crater

As last week’s full moon begins to wane, let’s take a look at lunar impact crater Tycho. Named for early Danish astronomer Tycho Brahe, it is often regarded as the finest example of a rayed crater. It’s rays, formed of material ejected by the impact that formed the crater, extend across a significat portion of the lunar surface. Another intereting feature of Tycho crater is it’s central peak, rising roughly 1.6km above the crater floor. As may be guessed from it’s sharply defined appearance, Tycho is a relatively young crater; it’s age estimated at 108 million years. It’s sharp appearance also makes Tycho an easy crater to find. Just look in the moon’s southern highlands, follow the rays back to their center, and it will be obvious which crater is Tycho. Start with low magnification to take in the intricate and beautiful system of rays, then push in with higher magnification for the crater itself. This is one crater worth a second look.

M13 in Hercules

Saturday, May 9th, 2009

As we move toward summer, one of the best sights for the backyard astronomer is globular cluster Messier 13 in the constellation Hercules. It is also one of the easiest globular clusters to find. The most obvious feature of Hercules is the trapezoid of stars known as the Keystone. M13 is located along the leading edge of the keystone, slightly closer to Eta then Zeta.

M13

Although closer than many globular clusters, M13 is still 25,000 light years away. Visible even with binoculars, it shows a wealth of stars through a typical small telescope. Don’t miss this telescopic treat this summer.