Tuesday, March 13, 2012

The Ellensburg Sky for the week of 3/17/12

Saturday: Mars is four and a half fists held upright and at arm’s length above the southeast horizon at 10 p.m. Its two small moons, Phobos and Deimos, are not visible in typical backyard telescopes. But they are an interesting study. The prevailing view among most astronomers is that they are captured asteroids. That makes sense given Mars’ proximity to the asteroid belt. But resent findings by European astronomers indicate that Phobos is very porous and made of material similar to the surface of Mars. This implies that Phobos may consist of chunks of Martian debris that was blasted off by numerous impacts and gravitationally bound together. Unfortunately, the Russian Phobos-Grunt probe launched late last year to collect material from Phobos crashed on Earth after malfunctioning. For more information about this new model of Phobos’ formation, go to http://goo.gl/g4cdp.

Sunday: Apparently, Venus and Jupiter had a falling out. Venus is moving away from Jupiter in the night sky. They are about three fists above the west horizon at 8 p.m. The much brighter Venus is about a half a fist above Jupiter. Watch them move farther apart as the week goes by, like a Kardashian woman and her NBA star.

Monday: Look up in the sky. It’s a plane. It’s a bird. No, it’s the vernal equinox. The vernal equinox!? Spring starts at 10:13 p.m. Pacific Daylight Time. The first day of spring is often called the vernal equinox. This label for the day is misleading. The vernal equinox is actually the point in the sky where the Sun’s apparent path with respect to the background stars (called the ecliptic) crosses the line that divides the stars into north and south (called the celestial equator). This point is in the constellation Pisces the fishes. At the vernal equinox, the Sun is moving from the southern region of background stars to the northern region. Since the Sun crosses the vernal equinox at night, tomorrow will actually be the first full day of spring.
Because the Earth slowly wobbles like a spinning top, the vernal equinox is slowly moving into the constellation Aquarius. By the year 2597, the vernal equinox will reach the constellation Aquarius and the “Age of Aquarius” will begin. Until then, we’ll be in “the age of Pisces”.

Tuesday: Still worried about 2012? Don’t be. Watch http://www.universetoday.com/94080/still-concerned-about-2012/.

Wednesday: Sirius, the brightest star in the nighttime sky, is two and a half fists above due south at 8 p.m.

Thursday: Tonight’s Moon is new. Don’t bother looking for it. The new moon is the phase where the Moon is directly between the Earth and the Sun. Hence the side of the Moon facing Earth is not receiving any sunlight and cannot be seen. The New Moon is not a big deal this month. But, May 20, the New Moon will be covering most of the Sun leading to an annular solar eclipse. What is an annular solar eclipse? More on that as the eclipse time draws nearer.

Friday: So far this week, I have written about Venus, Mars, and Jupiter. Do you even care about these planets or does another planet really catch your fancy? If you’d like to know what most people’s favorite planet is, go to http://www.pbs.org/wgbh/nova/pluto/favorite.html and click on “Launch Interactive”. The public TV special called “The Pluto Files” has set up a website in which astronomers give a 30-second pitch for why a certain planet is their favorite. After listening to the pitch, you may vote for your favorite planet. Of course, you may also do what most people do for political elections: vote for the candidate with the best name or the one with the most interesting campaign slogan. So whether you carefully consider each planet or simply “Swoon for Neptune”, “Jump for Jupiter”, or “Pick Uranus”, go to “The Pluto Files” and vote. Saturn will be holding a campaign rally tonight at 11 p.m., nearly two fists above the southeast horizon.

The positional information in this column about stars and planets is typically accurate for the entire week.

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