What’s Up This Week – May 9 – May 15, 2005

Photo of galaxy NGC 2903. Image credit: Zsolt Frei and James E. Gunn. Click to enlarge.
Monday, May 9 – Can you spot the very slender crescent Moon tonight? Look for it just after sunset low on the western horizon. Both bright Venus and the Plieades are to its west and will present a delightful challenge.

Before the Moon steals our early dark skies, let’s begin the week by studying a galaxy very similar to our own Milky Way – NGC 2903. Located less than two degrees south of Lambda Leonis, this magnificent 9.7 magnitude barred spiral can be spotted with binoculars from a dark location, and will be an easy small scope object. While the NGC 2903’s size and central bar closely resembles our own galaxy’s structure, the Hubble Space Telescope crossed the 25 million light year gap and found evidence of young globular clusters in its galactic halo – unlike our own old structures. This widespread star forming region is believed to be attributed to the gravity of the central bar. Small telescopes will show it as a lateral concentration across the central structure, while larger aperture will reveal spiral arms and concentrations of stars.

Tuesday, May 10 – Tonight give the Moon time to set and the constellation of Canes Venatici to rise as we go hunting the “Sunflower Galaxy” – M63. Located about a fist width southwest of the M51, you can normally spot it easily by scanning the area midway between Alkaid and Cor Caroli.

Originally discovered in 1779 by my hero Mechain, this bright galaxy is located about 37 million light years away and is believed to be part of a group of galaxies that includes M51. To binoculars it will appear as a faint misty oval, but larger scopes with optimal sky conditions will reveal the galaxy’s spiral arms as a grainy background that brightens considerably towards its center. Perhaps the most interesting feature of the M63 is its spiral arms. Most typical spiral galaxies contain two or three distinct spiral arms, yet this one’s structure is multiple short spiral arcs that remind many observers of a “celestial flower”. Scientific study of the M63 reveals that the galactic material at the edges of these arms is moving much faster than normal. Given the gravity of visible matter, this indicates the existence of dark matter within its structure.

Wednesday, May 11 – For viewers in south/central Australia and New Zealand, the Moon will occult Beta Taurii on this universal date. Please check IOTA webpages for details and times in your area.

So how about if we wait until the Moon sets and do a little comet hunting tonight? Let’s start with a familiar face – the “Magnificent Macholz”. Now faded to a soft magnitude 9, it can still be found with larger binoculars from a dark sky location. This evening will put the comet about equo-distant between Epsilon and Gamma Ursae Majoris and in the same field as star 73. Telescope users should still be able to see remnants of Macholz’ tail. For a little more challenge, locate 9/P Tempel 1 about 2 degrees southwest of Epsilon Virginis. At an estimated magnitude 10, Tempel 1 will be a bit fainter than Macholz, but far brighter than 13.5 magnitude NGC 4779 in the same lower power field.

Thursday, May 12 – For viewers in Florida, Bermuda and eastern Canada, the Moon will occult open cluster NGC 2331 on this universal date. Please check out this IOTA webpage for details. NGC 2331 is located roughly halfway between Beta and Epsilon Geminorum. At roughly magnitude 8, this scattered open cluster will be best detected with larger scopes during the occultation.

If you chose to view the Moon tonight, look for splendid dark crater Endymion on the terminator to the north. Normally its floor appears very smooth and very dark, but tonight it will seem to match its surroundings as the sunrise illuminates its west wall and the broad shadow of east wall defines its borders.

For viewers in western Europe, tonight would be a wonderful opportunity to spend some quality time with Jupiter. The great “Red Spot” will transit at 21:23 UT. Two of the galieans will add to the excitement as Europa’s shadow crosses the surface between 18:50 and 21:31 – followed by the ingress of Io’s shadow at 21:51.

Friday, May 13 – For viewers in Australia and New Zealand, the Moon will occult Iota Geminorum on the universal date. Please check IOTA webpages for further details.

If you are exploring the lunar surface tonight, be sure to look closely along the east boundary of Mare Nectaris. The bright cliff you see will be the Pyranees Mountains which holds crater Gutenburg in their grasp. This is a crater that has been filled with lava and terribly eroded over its lifetime. Its northeast wall has been broken by an impact known as Gutenburg E before the lava flood. The southern edge contains a very unusual mountain walled enclosure.

Saturday, May 14 – Tonight the Moon will be at apogee and will have reached its greatest distance of 404,600 km (251,407 miles). Let’s journey away to the lunar surface to view a very fine old crater – Theophilus. Slightly south of mid-point on the terminator, this crater contains an unusually large multiple peaked central mountain which can be spotted in binoculars. Theophilus is an odd crater, one that is a parabola – with no area on the floor being flat. Tonight it will appear dark, shadowed by its massive west wall, but look for sunrise on its summit!

Let’s turn our attention now to a splendid double star for the small telescope – Delta Corvi. Known as Algorab, this highly visible third magnitude star lies at the northeastern corner of the odd rectangle that forms the major pattern of Corvus. Its 9th magnitude companion is a wide split at 24 arcseconds away.

Sunday, May 15 – Would you like to see two planets in the same field of view? Then this morning would be well worth getting up early for as Mars and Uranus will only be about one degree apart. At +0.5 magnitude, reddish Mars will make a nice contrast with the 6th magnitude greenish Uranus. This will be very viewable in small binoculars and outstanding with the telescope.

Today is the birthday of Nicholas Louis de la Caille (or de Lacaille). Born in 1731, the French astronomer and mapmaker was the first to demonstrate Earth’s bulge at its equator. From 1751 to 1753, he had the great fortune to observe southern skies from the Cape of Good Hope. Putting his cartography skills to use, he mapped the southern skies and established the 14 constellations that remain in use to this day.

For lunar viewers tonight, enjoy the bright crests of the Caucasus Mountains with prominent craters Eudoxus and Aristoteles to the north.

Until next week? Ask for the Moon, but keep reaching for the stars! May all your journeys be at Light Speed… ~Tammy Plotner