Bakersfield Night Sky – May 17, 2014
By Nick Strobel
By the time this column appears in print, the Bakersfield College Centennial Commencement will have already taken place Friday evening. As I write this several days before, we're gearing up for a great event with a dinner, music courtesy of Mento Beru, alumni march around the track, and fireworks! Finals are done and the William M Thomas Planetarium will be closed during the summer. The all-dome video projection system's computers are being sent back to the vendor, Spitz, for repairs. I hope things can get fixed in time for the start of the fall semester.
In my previous column I talked about the Eta Aquariid meteor shower that peaked near the beginning of the month. Near the end of May is the possibility of an impressive new meteor shower. The predicted new meteor shower is expected to peak the night of May 23rd/24th. If the predictions are correct, this new shower would be worth checking out because of large number of meteors that may be seen every hour. Numbers quoted are up to several hundred! A meteor shower results from the Earth plowing through the dust trail left behind by a comet when it nears the Sun. The dust grains are the size of sand grains or smaller. They hit the upper parts of the atmosphere far faster than a speeding bullet and burn up many tens of miles above the surface. The comet making Friday night's meteor shower is Comet 209P/LINEAR
Comet 209P/LINEAR was discovered in 2004 by the Lincoln Near-Earth Asteroid Research (LINEAR) program that hunts for near-Earth asteroids using an automated system of telescopes at White Sands Missile Range in Socorro, New Mexico. Along with over 2400 near-Earth objects, the LINEAR program has found 279 comets (and counting). Comet 209P takes 5 years to orbit the Sun in an elliptical orbit that takes it out almost to Jupiter. (Yes, we need to come up with a nice name for the comet, but when you have 279 comet discoveries with this program alone, you run out of names!) Jupiter's gravity can nudge the comet and change its orbit. One close encounter with Jupiter in February 2012 changed the orbit of the comet and its dust trails enough so that the orbit comes to within just 280,000 miles of the Earth. Since the dust trail is a bit spread out, that means the Earth can run into it, resulting in a meteor shower.
Several researchers who specialize in the dynamics of comets and their dust trails have made predictions of more than 100 meteors per hour with a very narrow peak of just three hours centered around midnight of May 23rd/24th our time. Most meteor showers will last several days on either side of their peak but not this one. These meteors will be slow: traveling at "only" 18 km/sec (40,000 mph). Meteors in other showers travel two to three times faster. The meteors from Comet 209P will appear to radiate out of a point near the north star, Polaris, though the location is within the boundaries of the faint constellation Camelopardalis. Therefore, the meteor shower is called the "Camelopardalids" and good luck to all of the TV and radio media people who try to pronounce that mouthful.
Use the pointer stars at the end of the bowl of the Big Dipper part of Ursa Major to point to Polaris, roughly a third of the way up above the northern horizon. About a third of the way between Polaris and the nose of Ursa Major is the radiant. The first star chart below shows the location of the radiant. The Waning Crescent Moon won't rise until after 3 AM which is after most of the show should be over. You'll probably see most of the meteors about half way between the radiant and the zenith point straight overhead.
No binoculars or telescope needed for observing meteors---just a good set of eyes. Find a nice dark location miles away from any street lights so you won't have all of that light pollution washing out the fainter meteors. You'll need a nice reclining chair and warm clothing and a friend or two to help keep you company and awake! Kern Astronomical Society members will be gathering at the Lockwood Valley site, just a bit beyond Frazier Park. I hope the skies will be clear!
Last Saturday was the first of the public star parties, the Kern Astronomical Society hosts during the spring, summer, and fall. They'll be having telescopes set out at Panorama Park near where Linden Ave meets Panorama Drive (just west of Greenlawn Mortuary/Cemetery) from 8 to 10 PM, depending on weather. Last Saturday, the strong winds made them pack up by 9:30 PM but hopefully, future nights will be more pleasant. The free public star parties will take place on the Saturday closest to the First Quarter Moon, so future ones will be June 7, July 5, August 2, September 6, October 4, and November 1. See the KAS website at www.kernastro.org for more details and a map to the observing site.
In other space news, one piece that crossed my computer screen was the discovery of a star that appears to be one of the Sun's siblings, born from the same cloud of gas at the same time as the Sun, 4.6 billion years ago. Ivan Ramirez of the University of Texas at Austin leads the group that is looking for the Sun's sibling stars. Their hoping that the search will help determine where in the galaxy the Sun formed. The first star found in that search is HD 162826 (the "HD" is for the Henry Draper catalogue). It is about 110 light years away in the constellation Hercules about halfway between the keystone part of Hercules and the bright star Vega in Lyra. The first chart below shows its location but you'll need a good pair of binoculars to spot it. It is about 15% more massive than the Sun.
Ramirez's team used spectroscopy to determine the star's spectrum and motion through space. The star's light was spread out into its rainbow of colors to reveal the barcode pattern that tells us the composition of a star, its temperature, and its motion along the line of sight from how much the barcode pattern was shifted. The shifting of the barcode pattern is due to an effect called the doppler effect. The greater the shift, the faster the star is moving. If the shift is toward longer wavelengths (a "red shift"), the object is moving away from us. If the shift is toward shorter wavelengths (a "blue shift"), the object is moving towards us. Combining the line-of-sight velocity with its very slow motion across the sky over many years, we can determine its true 3D motion in space and, therefore, its orbit in the Galaxy. The amounts of the elements barium and yttrium in HD 162826 were particularly helpful in determining its chemical likeness to the Sun.
Stars are born in batches and over hundreds of millions of years, they drift apart from each other with their attendant planets in tow. There were probably several hundred to a few thousand stars formed in the Sun's cluster and now they are spread around the Galaxy. The news story from UT Austin says that once several more siblings of the Sun are found, the astronomers will be able to run the orbits backward in time to find their common starting point: their birthplace. Of that claim I'm a bit doubtful since a lot has happened in the Galaxy over 4.6 billion years of time. The Sun has made over 18 orbits around the Galaxy in that time.
If the intervening years had been quiet for the Milky Way Galaxy, then, yes, we could run those orbits backward. However, the Milky Way hasn't been the nicest of galactic neighbors. It has eaten several small galaxies that have wandered in too close. That's why the Milky Way is among the larger of the galaxies out there, though there are some other huge galaxies that have been especially gluttonous. When galaxies merge, stars don't hit each other because they are so far apart compared to their size. In our part of the Galaxy, the star spacing is such that if Pluto's orbit was shrunk down to the size of a quarter coin, the next star would be about 80 meters (big steps) away. Imagine trying to hit one quarter with another quarter from 80 big paces away and remember that the quarter represents Pluto's entire orbit, so the Sun would be microscopic.
Stars won't hit each other but they can sure mess up each other's orbits from their mutual gravity pulling on each other. On the other hand, if they do find that the solar sibling orbits do all intercept at a common point 4.6 billion years ago, then that location could very well be the birthplace since the small galaxy mergers hadn't messed up the solar siblings orbits enough to make a backward convergence impossible to find.
In our sky tonight, see if you can spot Mercury low in the west near the tip of the horns of Taurus. At 8:30 PM it will be about a fist width at arm's length above the horizon. This week will be its best appearance all year. Further up will be bright Jupiter. Jupiter will be the brightest thing in the western sky. At a little after 9 PM, Jupiter and and the next largest planet, Saturn, will be at about the same altitude above the horizon. Jupiter will be about a third of the way above the horizon among the stars of Gemini. Jupiter is almost at the left brother of the twins, Pollux. Saturn will be among the stars of Libra in the southeast. Saturn is putting on a good show for us as we pass by it in our faster orbit. Its rings have really opened up for a great view through a telescope. Be sure to check it out at one of the public KAS public star parties this spring and summer.
About halfway between Jupiter and Saturn will be bright orange-red Mars in the south a little after 9 PM. It has now moved past the double star Porrima at the west edge of Virgo. Mars is nearing the end of its retrograde motion so it is getting dimmer but it is still plenty bright and easily visible under even light-polluted skies. To Mars's left will be the bright blue-whiteSpica and about two-thirds of the way up in the sky will be bright yellow-orange Arcturus at the end of kite-shaped Bootes. The second and third sky charts below show the evening sky.
The Waning Gibbous Moon will rise with the stars of Sagittarius about 11:15 PM. Venus will be visible at about 4:30 AM rising below the Great Square of Pegasus among the dim stars of Pisces. If you see a super-bright "star" in the east before sunrise, you're looking at Venus.
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