Friday, June 29, 2012
The Ellensburg sky for the week of 6/30/12
Saturday: The constellation Cepheus the king is about four fists held upright and at arm’s length above the northeast horizon at 11 pm. Cassiopeia the queen is about one and a half below her husband Cepheus. Cassiopeia looks like the letter “W” and Cepheus looks like a house on its side with the roof peak pointing towards the west. Cassiopeia and Cepheus revolve around the North Star every night like a happy couple going through life together.
Sunday: Wednesday night, while you are looking at an explosion of fireworks, the NASA spacecraft Kepler may be looking at an “explosion” of exoplanets. So far, Kepler has found 74 planets whose presence has been confirmed by other means and evidence of 2,321 planet candidates. Something is called a planet candidate when the light from a star being observed by Kepler dims in a systematic way. Astronomers still need to compare the pattern of dimming with the potential pattern of star wobble caused by being tugged on by one or more planets before they can say for certain that they have actually found planets orbiting these stars. But if even half of these stars show the characteristic wobble, it will more than double the number of planets known to orbit other stars, also known as exoplanets. And this is only the beginning. The Kepler spacecraft is monitoring the brightness of over 156,000 stars in the constellations Cygnus the swan and Lyra the lyre. This region is midway between the bright stars Deneb and Vega. It is about the size of your hand held at arm’s length and is about six fists held upright and at arm’s length above due east at 11 p.m. For more information about the Kepler mission, go to http://kepler.nasa.gov/.
Monday: Last week, I wrote about Mizar. This week, I need to warn you not to confuse Mizar with its rhyming brother Izar in the constellation Bootes. Izar is also a binary star with about the same apparent brightness. And both were featured in different episodes of Star Trek. Izar was featured in the Star Trek episode “Whom Gods Destroy” from the original series. It is the base of Fleet Captain Garth, a former big shot in the federation and one of Kirk’s heroes before he went insane. Garth kidnaps Kirk and Spock before eventually being out smarted. Mizar doesn’t play as big a role in its episode. It is the star of the home world of one of the alien species in The Next Generation episode “Allegiance”. Izar is one fist above the bright star Arcturus and seven fists above the south horizon at 10 p.m. Mizar is seven fists above the northwest horizon at this time.
Tuesday: July is typically the month when the antlers of a young buck push out of its head so some Native American groups call this month’s full moon the Full Buck Moon. Tonight, the Full Buck Moon is in the constellation Sagittarius the archer.
Wednesday: Hot enough for you? Don’t blame the Earth-Sun distance. Surprisingly, the overall temperature of the Earth is slightly higher in July, when the Earth is farthest from the Sun, than in January, when it is closest. That’s because in July, the Northern Hemisphere is tilted towards the Sun. (This is the real cause of the seasons.) The Northern Hemisphere has more land than the Southern Hemisphere. Thus, in July, the large amount of Northern Hemisphere land heats up the entire Earth about two degrees Celsius warmer than in January. In January, the watery Southern Hemisphere is tilted toward the Sun. But, water does not heat up as fast as land so the Earth is a few degrees cooler. The distance between the Earth and Sun is its greatest today, 152.1 million kilometers. This is called aphelion from the Greek prefix “apo” meaning “apart” and Helios, the Greek god of the Sun.
Thursday: Saturn and Mars are both in the constellation Virgo for the next few weeks. At 11 p.m., Saturn is two fists above the southwest horizon and a half a fist above the bright bluish star Spica. The reddish planet Mars is a little more than a fist above the west-southwest horizon.
Friday: The bright star Antares at the heart of Scorpius the scorpion is a fist and a half above the south horizon at 11 p.m.
The positional information in this column about stars and planets is typically accurate for the entire week.