What’s Up This Month – April 2009

There’s good news and bad news as March turns to April and a long winter finally fades.

The bad news: the spring sky has nowhere near as many bright deep-sky objects for small telescopes as winter, at least for northern-hemisphere observers.

The good news?  All five bright planets are visible this month, so you still have lots of observing to do.  And if you have a 6 to 8-inch or larger scope and dark sky, this is a great time of year to go hunting for faint deep-sky fuzzies in the galaxy fields of Leo, Virgo, and Ursa Major.

Celestial Events

• Lyrids Meteor Shower. This shower, with a radiant near the bright star Vega, is not usually impressive.  But there have been exceptions some years.  The shower peaks after midnight on April 22.

• Moon Occults Venus. A thin crescent Moon will pass in front of Venus.  This will be visible in most of North America on the morning of April 22.  The best view is on the west coast, since it occurs near dawn local time when the sky will not be fully lit.  In eastern North America, the occultation occurs in the mid-morning.  A telescope will help you see the crescent moon and Venus, but you need to know exactly where to look.  If you have a go-to mount, you are all set.  If not, but you have time, train your telescope on the moon at dawn when it’s still visible.  Then track the moon over the next couple of hours until you see Venus pass behind.  Yes… Venus is visible in the daytime in a telescope.

• Full Moon. It’s full on April 9 at 10:56 Eastern.  Remember… the glare of a full moon makes it much harder to see deep sky objects.  So maybe this is a good night to clean your eyepieces or catch up on your sleep!

• Mercury, Moon, and Pleiades. In the best show of the month, on April 26, the Pleiades sparkle in the early evening sky between a thin crescent moon and the planet Mercury.  You’ll need a clear view of the western sky just after sunset.  This should make for fine viewing with your naked eye or with binoculars, and is well worth the effort to photograph with a telephoto lens.

The crescent Moon, the Pleiades, and Mercury near sunset on April 26.

Don’t forget 100 Hours of Astronomy will run from April 2 to 5, local time.  Get out and see the stars, in person or online, during this once in a lifetime event.

Planets

• Mercury. This small planet turns around the far side of the Sun at the end of March and wheels into view in the evening sky in mid-April.   Never far from the Sun, Mercury reaches its greatest elongation (it’s furthest angular distance from the Sun) on April 26.  It will be roughly 20 degrees above the horizon at sunset in the northern hemisphere on that day, and about 8 degrees above the horizon in the southern hemisphere.  A telescope shows the disk 40% illuminated.  The prettiest show this month, as we said above, involves Mercury, the Moon, and the Pleiades on April 26.

• Venus. After months of putting on a spectacular show in the evening sky, Venus has swung around the Sun to become the “morning star”.  It’s still tremendously bright, although it’s quite close to the Sun and rises just an hour before sunrise.

• Saturn. Not far from opposition, Saturn is primed for viewing in the lower part of Leo.  The rings are almost edge-on.  Even a small telescope will reveal Titan, Saturn’s largest moon.  With the rings out of the way, can you see any cloud bands in the upper atmosphere of the planet?  A yellow filter may help.

• Jupiter and Mars. Both are visible low in the southeast sky before dawn.  Mars is far away and tiny right now.  Jupiter will put on a good show later this summer when it’s primed for summer-night viewing in Sagittarius.

Sights To See

There are dozens of galaxies to see in spring as we look out of the plane of our galaxy into intergalactic space.  Two of the brightest galaxies, visible even in good-sized binoculars in dark sky, are M65 and M66 in the haunches of Leo.  In a telescope these spiral galaxies look like two eyes peering at you from deep space.  If you have dark sky, try to see the nearby spiral NGC 3628, just a couple degrees away.  These three galaxies are gravitationally associated and form the small “Leo Triplet” galaxy cluster.  M65, M66, and NGC 3628 lie roughly 22 million, 36 million, and 35 million light years away, respectively.

The spiral galaxies M65, M66, and NGC 3628 in Leo (lower left)

“Waiting for spring stars
Cherry blossoms, galaxies…
I pretend to work.”