Thursday, May 23, 2013

The Ellensburg sky for the week of 5/25/13

Saturday: Mercury, Venus, and Jupiter are neighbors low in the west-northwest sky just after sunset all week. Tonight at 9 p.m., Venus is on the bottom of a small triangle, Jupiter is to the upper left of it and Mercury is right above it. As the week goes by, Jupiter moves down while Mercury and Venus move up. By Wednesday, they are in a line with Jupiter on the bottom and Mercury on the top.

Sunday: Are you planning on a late Saturday night? If so, look six fists above the southern horizon at 2:39 a.m. You’ll see the very bright International Space Station (ISS) moving from the Earth’s shadow into position to reflect the Sun’s light toward Ellensburg. The ISS will be the brightest point of light in the sky. In fact, this is the brightest the ISS will be all week. If you’d rather not stay up so late but are still interested in finding out when the ISS is visible from your location, go to and sign up for free ISS alerts to be sent to your email or phone.

Monday: The constellation Aquila the eagle is starting its migration across the summer evening sky this month. Aquila, marked by its bright star Altair, rises above the east horizon at about 11 p.m. Not all animal migrations are fully understood by scientists. We might be inclined to attribute bird migrations to instinct. This answer certainly did not satisfy the theologian C. S. Lewis. In his short work “Men Without Chests”, he wrote, “to say that migratory birds find their way by instinct is only to say that we do not know how migratory birds find their way”. In science (and theology), Lewis is telling us to look for real causes and not simply labels such as instinct. The cause for Aquila’s migration is the Earth orbiting the Sun. As the Earth moves around the Sun, certain constellations move into the evening sky as others get lost in the glare of the setting Sun.

Tuesday: Antares is one fist above the south-southeast horizon at 11 p.m.

Wednesday: Cygnus the swan flies tonight. Deneb, the brightest star in the constellation, whose name means “tail” in Arabic, is two fists above the northeast horizon at 10 p.m. Cygnus’ wings make a vertical line one half a fist to the right of Deneb. Its head, marked by the star Albireo, is two fists to the right of Deneb. While Deneb is at the tail of Cygnus, it is at the head of the line of bright stars. It is 160,000 times more luminous than the Sun making it one of the brightest stars in the galaxy. It does not dominate our night sky because it is 2,600 light years away, one of the farthest naked eye stars. If Deneb were 25 light years away, it would shine as bright as a crescent moon. Compare that to Vega, which is 25 light years away. Vega is three and a half fists above the east-northeast horizon at this time.

Thursday: Good night little doggie. Procyon, the brightest star in Canis Minor, the little dog, is just one fist above the west horizon at 10 p.m. Over the next couple of weeks, it will be too close to the setting Sun in the sky to be visible.

Friday: Late tonight, the moon rises in the third quarter phase. By tomorrow morning, it is in the east-southeast sky in the constellation Pisces.

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

No comments: