Looking Up May 2012

As we spin towards summer, the length of the day continues to increase, but more slowly. Early in May the sun rises about 6 am and sets about 8:10 pm; near the end of May it rises about 5:45 am and sets about 8:25 pm. (All times are EDT.)

Phases of the Moon: Full on the evening of May 5; 3rd quarter on May 12, New on May 20; and 1st quarter on May 28. On May 20 the Moon will partially cover the Sun in what is called an annular eclipse. The eclipse will not be visible from Maryland, but if you are planning to be anywhere north-west of a line from central Texas through central Wisconsin, you might be able to see it in the late afternoon before sunset. Be sure to use safe viewing techniques (eg. Observing Solar Eclipses Safely).

Evening Sky: Auriga (the Charioteer), with its bright star Capella, and Gemini (the Twins) (bright stars Castor and Pollux) dominate the western sky after sunset. At this time of year in the evening, the Big Dipper very high in the sky, making it quite easy to use the Pointer Stars to find the North Star, aka Polaris. Bootes (the Herdsman) with its bright star Arcturus is well up in the north-east. Mars is high in the sky towards the south-west, still near the bright star Regulus in Leo (the Lion). Saturn is high in the sky towards the south-east, near the bright star Spica in Virgo (the Young Woman). Venus is at it most brilliant in early May, gleaming high above the western horizon, poised for its plunge back towards the Sun and its Transit of the Sun on June 5th. Early in May Venus sets more than 3 hours after sunset. As the month progresses, Venus appears lower and lower in the sky, until by the end of May it will set a mere 30 minutes after sunset. Viewed with good binoculars or a small telescope, the sunlit disk appears as a fat crescent early in the month; during the month, the crescent will grow in length while it thins to a sliver, as Venus “catches up with” the Earth as the two planets move in their orbits around the Sun. The crescent phases of Venus were one of the key observations that lead Galileo to conclude that the Earth is not the center of motion for the solar system.

Pre-dawn Sky: For those who start the day early, or are just getting off the 6pm-3am shift, the pre-dawn sky holds some treats. Early in May, Sagittarius (the Archer) is rising in the south-east, and Scorpius (the Scorpion), harbinger of summer, with its bright red star Antares, is well up towards the south. The name “Antares” is of Greek origin, and means “not Mars”. If you are out between 1 am and 2 am in the morning early in May, take a moment to compare Antares with Mars, which is low on the western horizon, and you may understand why that star received such a name. In addition, Saturn is still high in the sky towards the south-west, and does not set until around sun rise. If the sky is dark enough in your area, you may see the faint glow of the Milky Way rising up from Scorpius and Sagittarius and arcing above the eastern horizon through Aquilla (the Eagle) and Cygnus (the Swan).

That’s all for this month.   And, as the great Jack Horkhemier used to say, Keep Looking Up!

Helen Hart, 30 April 2012; references:  the Astronomical Calendar, Starry Night planetarium program, USNO Astronomical Data Services.


Spring Star Party, April 27, 2012

We are a GO for tonight! But it’s going to get cold, so be sure to dress for 30-degree temperatures!

The APL Astronomy Club’s Spring Friends & Family Star Party will be held Friday, April 27th, starting at 8:00 pm (club telescope set up starts at 7:30). Check for a Weather Status Update at this web site on April 27th in the afternoon.

Star Party on the West lawn near the Big Radio Dish

APLers and their friends and families are invited. Club members will have several telescopes out for your viewing pleasure. Bring your own optics if you have ’em – the more, the merrier! NO FLASHLIGHTS

Where: on the lawn next to the Big Dish on the West side of the Main Campus, outside the perimeter fence.

Dress for temperatures at least 10 degrees colder than predicted.

Park near the turnstile entrance by building 21, or near the building 23 lobby entrance.

Sun: sunset 8 pm EDT; end of civil twilight about 8:30 pm.

Moon: waxing crescent, 6.5 days old (reaches 1st quarter the morning of Apr. 29)

Venus: waning crescent (lighted disk similar to Moon’s), 38 degrees elevation at 8 pm EDT, visual magnitude -4.5.

Mars: past opposition, apparent diameter ~10 arc-seconds, 58 degrees altitude at 8 pm EDT, visual magnitude -0.1.

Saturn: rising in the East before sunset, reaches an altitude of 25 degrees by 9 pm EDT (01:00 UT); apparent diameter of rings ~43 arc-seconds, visual magnitude 0.3.

Jupiter: sets about an hour after the sun.

Uranus, Neptune, Pluto: in the early morning sky, not visible in the evening.

Orion nebula (but it will set early), M44 star cluster, associated star clusters in Auriga, various double stars.

May Meeting

APL ACWhat: APL Astronomy Club monthly meeting
Where: Gibson Library room L-2
When: Wednesday, May 16, noon to 1:00 pm

This month’s topics: Preparation for the Venus Transit Party on June 5th, elections in June (!), and member observing reports.

(Steve Conard’s talk about his observations of a possible satellite of asteroid Agamemnon had to be postponed; we’ll reschedule him as soon as possible.)

Open to anyone with an interest in astronomy.


April Meeting

APL ACWhat: APL Astronomy Club monthly meeting
Where: Gibson Library room L-2
When: Wednesday, April 18, noon to 1:00 pm

This month’s topics: April Star Party, prep. for Venus Transit Party, members’ observing reports.

Open to anyone with an interest in astronomy.


MOVED Solar Star Party, Bldg 1 Main Cafeteria patio


What: Solar Observing
Where: Building 1 Main Cafeteria Patio
When: Tuesday, April 17, noon to 1:00 pm

Come view the Sun, our very own star, with the APL Astronomy Club. Count sunspots, see faculae and plages and maybe granulation and spicules, and compare the view through different kinds of equipment. Venus may also be visible in regular telescopes.

Open to anyone on campus who is interested.

If it’s too cloudy the event will be canceled.  (Note:  the previous 4 Sun Parties were canceled due to clouds.   Any one care to predict the weather at noon on April 16??)