Bakersfield Night Sky – June 4, 2011
By Nick Strobel
Go out tonight, face south-southeast, and look a bit more than half way up in the sky at around 9:30 to 10 PM. You will three bright stars making a triangle tipped over with the top facing northward as shown in the first star chart below. Now, to see if you are as smart as a fifth grader, what type of triangle is it? Two sides are equal—an isosceles triangle (bonus points if you can correctly spell the triangle type without looking it up...like I had to). The top of the isosceles triangle pointing northward is the orangish star Arcturus, in Bootes. The lowest star of the tipped over isosceles triangle on the right is Spica in Virgo. The star above Spica, the last point of the isosceles triangle (if I spell "isosceles" enough times I won't have to look it up) is actually not a star—that's Saturn. Saturn is right next to a dimmer star of Virgo called Porrima, so the two look like a double star without binoculars. With a telescope you would see that Porrima is a true double star, a binary system with two stars orbiting each other, a very common sort of system in our galaxy (single stars like the Sun are in the minority). Saturn has been drawing closer and closer to Porrima as the weeks have gone by and will stop its westward drift in the middle of this month. For all of June, Saturn will be within half a degree of Porrima.
The two stars of Porrima are about four times hotter than the Sun and their very elliptical orbits around each other means that habitable planets probably could not exist in that system. Porrima's stars elliptical orbits carry them between 5 AU and 81 AU apart from each other, where 1 AU is the average distance between the Earth and the Sun. Habitable planets can exist in binary systems if the two stars orbit very close to each other so that stable planet orbits could exist in the habitable zone surrounding both of the stars far from both of them—the two stars would essentially act as one star (Star Wars fans: recall Tatooine). Habitable planets can also exist in binary systems if the two stars remain very far from each other so that stable planet orbits in each of the star's habitable zones could exist.
Saturn is above our horizon even before sunset so be sure to check it out with the Kern Astronomical Society's telescopes outside of Russo's Bookstore in the Marketplace next Saturday (June 11th). The telescopes will be set out for anyone to look through from dusk to about 9:30 PM. Further north will be the bowtie or butterfly shape of Hercules at about the same altitude as Spica. Lower down and slightly further north of Hercules will be the bright star, Vega, one point of the other triangle in the sky, the Summer Triangle made of Vega, Deneb at the tail of Cygnus the Swan, and Altair at the neck of Aquila the Eagle (see the third star chart below). You will need to wait until about 10:30 PM to easily see all of the stars of the Summer Triangle. Tonight, a thin sliver of the Moon (in a waxing crescent phase) will be visible low in the west after sunset to the left of the two bright stars of Gemini, Pollux and Castor. Next Saturday evening for the public star party at Russo's, the Waxing Gibbous Moon will be left of Spica in the south.
Early morning observers will be able to see the two brightest planets of the sky, Venus and Jupiter low in the east about 30 minutes before sunrise. Jupiter will be the upper one of the two and it will be below the Great Square part of Pegasus. They will outshine any other object in the pre-dawn sky for the next couple of weeks. Between Venus and Jupiter will be the dimmer orange-red planet, Mars, on the line drawn between the two bright planets—see the second star chart below. Venus and Jupiter are now over an outstretched hand at arm's length apart from each other and they will continue to move apart as Venus moves closer to the Sun as seen from Earth. Mercury is now lost in the glare of the Sun. We will be able to see Mercury again in the evening sky toward the end of the month.
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