Bakersfield Night Sky – May 21, 2011
By Nick Strobel
Early morning observers will still have the best views of the planets with Venus, Jupiter, Mercury, and Mars clustering close together low in the east about 30 minutes before sunrise. Find the Great Square of Pegasus (diamond shape now as it rises tipped a bit) and then look down below close to the horizon for two very bright "stars"—Jupiter and Venus (see the first chart below). Earlier this month, the two brightest, Venus and Jupiter, were in a close dance with the other two tagging along but now Jupiter is leaving the party. Jupiter is now about a clenched fist held at arm's length away from Venus with Jupiter to the upper right. By month's end Jupiter will be an outstretched hand (held at arm's length) away from Venus. The Waning Crescent Moon will pass by the morning planets the last three mornings of the month.
Evening observers will have to settle for Saturn and the Moon but both are great views through a telescope if you have access to one. Saturn will be due south at around 9:40 PM and the Waning Gibbous Moon will rise at about 12:30 AM (half hour after midnight)---see the second chart below. The Moon will be on the right side of Capricornus throughout the early morning hours. Saturn will be the brightest thing in Virgo but the bright star Spica on the left side of Virgo will give it some good competition. Saturn is still slowly creeping westward toward the star Porrima, a binary star system that can be split (seen as two stars) only with a telescope. Over the next 80 years the two stars of Porrima will get farther apart before drawing closer again.
To the left of Saturn and Spica in Virgo in the evening sky will be the very bright star Arcturus in Bootes. If you have good eyes and a dark sky, you might be able to see that Arcturus has an orange tint to it. That color is because it is 1500° C cooler than our Sun so its surface is "only" 4020° C. It is a dying star that has puffed out to be a "giant" star about 25 times the diameter of the Sun but having just 1.5 times the mass of the Sun. The constellation Bootes looks like a kite on its side with Arcturus near the tail end. Below the wide end of the kite is a backward "C"-shaped constellation called Corona Borealis (the northern crown). Even closer to the horizon now becoming visible in the evening sky is a group of stars that looks like either a bow tie or a butterfly. That is the main part of Hercules, the strong man of Greek mythology. The right part of the bow tie or butterfly is actually the upper part of Hercules' body so he is a bit upside down on our sky. The left part of the bow tie or butterfly looks like a keystone and is often referred to as such. As Hercules is rising, the keystone is tipped over a bit. If you scan along what would be the right side of the keystone if it was upright, you would come across a fuzzy object about one-third of the way down from the top of the keystone. That is a globular cluster called "Messier 13" or simply "M13". I think I have been able to barely spot it without any binoculars under a very dark sky but the key words there are "think" and "barely". With a telescope M13 you can easily see the sparkling hundreds of thousands of stars in a spherical ball. The light from those stars in M13 just reaching your eye now left M13 over 25,000 years ago (but it is still well within our galaxy).
The William M Thomas Planetarium is closed during the summer after a great spring season of shows. Shows at the Planetarium will begin again in mid-September. I will have schedule of Fall shows posted on the Planetarium's website no later than the last week of August. When the schedule is posted, tickets will be available in the BC Ticket Office for the entire Fall season of shows.
Want to see more of the stars at night and save energy? Shield your lights so that the light only goes down toward the ground. See www.darksky.org for how.
Director of the William M Thomas Planetarium at Bakersfield College
Author of the award-winning website www.astronomynotes.com