Bakersfield Night Sky – April 16, 2011
By Nick Strobel
Astronomy Day last Saturday turned out well despite the occasional cloud blocking the Sun every now and then for the solar viewing. Displays and some workshops took place in the Gym and some other workshops were in nearby classrooms. Glenn Dunbach, one of the Foothill High School science teachers, joined me as I took folks on a LONG walk of the solar system from one end of the campus to the other. Even with that we got to just Uranus. Neptune and Pluto would be in Voorhies Elementary, across the street from Foothill. Last year I think it was about 90 degrees doing the solar system walk so I was grateful for the cooler temperature. The master mind behind the whole event, Steve Collett (another Foothill High School science teacher), wandered around the Gym dressed as Galileo---the costume was quite good! That evening over a hundred folks braved the cold night to see Saturn, the Waxing Crescent Moon, the Orion Nebula, some double stars, and more. Yes, it was a good day and exhausting! Glenn and I hiked the campus four times. My bed felt especially nice that night when I got home.
A week later, what does the evening sky offer? Saturn and a Waxing Gibbous Moon! Saturn is the lone planet in the evening sky. Usually fairly bright compared to the other stars, tonight it will be a bit washed out with the almost full Moon to the lower right of Saturn. If you can see a "star" to the upper left of the Moon in tonight's sky, it will be Saturn (see the first star chart below). Saturn has been moving retrograde (backward or westward away from the bright star in Virgo, Spica. At the beginning of the month, Saturn was at "opposition", or directly opposite the Sun in our sky, so it was rising as the Sun was setting. Now Saturn is above the horizon before sunset. Saturn will end its retrograde drift in early June.
The first star chart also shows other interesting sights in the eastern evening sky. Almost at the same height above the eastern horizon as Saturn, a small turn northward will be the bright star Arcturus in Bootes. Although Bootes is supposed to be a shepherd, I look for the shape of a kite on its side as Bootes is rising. The same time tomorrow night the Moon will be full and closer to the eastern horizon below the bright star Spica. Above Arcturus is the very dim constellation Coma Berenices, named after Queen Berenice II of Egypt who lived in the third century BC and according to legend sacrificed her long hair. Coma Berenices means "Berenice's Hair". At about 9 PM if you go straight above Arcturus in Coma Berenices you will be looking in the direction of the Coma Cluster, a rich cluster of galaxies about 320 million light years away. You will need a telescope to see it, though. It has mostly elliptical galaxies with relatively few spirals in it because it is a well-developed cluster. When spiral galaxies collide with other large galaxies, the spiral structure is usually messed up and the result is an elliptical sort of galaxy. Over many hundreds of millions of years the spiral galaxies are cleared out of the central regions of rich clusters leaving a majority of elliptical galaxies. A rich cluster like Coma will also usually have a giant elliptical galaxy or two that have grown enormous by "cannibalizing" other galaxies that come too close. A little further right (south) in the area of the sky between Virgo and the star Denebola at the end of Leo is a galaxy cluster closer to us called the Virgo Cluster. At only 54 million light years away, it is the closest large cluster to us with over 1300 galaxies in it, including some giant ellipticals. One of the giant ellipticals is called Messier 87 and it has a supermassive black hole at its center with a mass of 6 or 7 billion times the mass of the Sun. The rest of M 87 is about a thousand more massive than that.
Further north on either side of the end of the Big Dipper's handle (the tail of Ursa Major) are two gorgeous face-on spiral galaxies, Messier 51 (Whirlpool Galaxy) and Messier 101 (Pinwheel Galaxy). Because of their beauty, they are often the subject of astronomy photographs. The images of them taken with the Hubble Space Telescope are stunning. M 51 is about 31 million light years away and M 101 is a bit closer at 25 million light years away. M 51 also has a supermassive black hole at its center with two dust rings that make an "X" centered on the black hole, so "X" really does mark the spot!
Early morning observers will see bright Venus rising in the east about an hour before sunrise. It has now moved to below the west end of Pisces that in turn is below the Great Square of Pegasus. At the end of the month those of you who get up before sunrise will have a beautiful view of a thin Waning Crescent Moon near Venus—see the second star chart below. The Moon and Venus will be joined by three other planets Mercury, Mars, and Jupiter, low in the east though you may need to use binoculars to spot all of them against the brightening dawn sky. Uranus will also be in the same direction. Strange that I haven't read anything on the internet about the close grouping of all of those planets with the Moon on the sky leading to some sort of disaster. Hmm... it must be because Saturn isn't among them too. Yes, that must be why. Or could it be because only a slim sliver of a Moon is with the planets? Or...
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