The Ellensburg WA sky for the week of 3/16/19

Saturday:  Ask someone which day in March has the same duration day and night. Go ahead, ask someone. Why are you still reading this? I can wait. If that person said the first day of spring, they are wrong. Today, four days before the first day of spring, is the date in which day and night are closest in duration in central Washington. There are two main reasons for this. First, the atmosphere acts like a lens, bending light from the Sun above the horizon when the Sun is actually below the horizon. This makes the Sun appear to rise before it actually rises and appear to set after is actually sets. Second, spring starts when the center of the Sun passes through the point called the vernal equinox. But, the Sun is not a point. The upper edge of the Sun rises about a minute before the center of the Sun and the lower edge sets a minute after the center of the Sun. Thus, even if we didn’t have an atmosphere that bends the sunlight, daytime on the first day of spring would still be longer than 12 hours.

Sunday: Many artists have sung the song “Blue Moon”. But few have sung the song “Blue Planet”. It goes, in part “Blue Planet, you saw me standing with 27 others. Rolling around like a barrel. Without close sisters or brothers.” It’s about the planet Uranus, which orbits the Sun in a rolling motion and has 27 moons. Every one of Uranus’ moons is named after characters in works by William  Shakespeare or Alexander Pope. Uranus is two fists above the west horizon at 8 p.m., easily visible with binoculars. First find Hamal and Sheratan, two stars of similar brightness, three fists above due west and a half a fist apart from each other. Then move your binoculars from Sheratan, the lower and dimmer of the two, toward Mesarthim, a star about half as bright to the lower left of Sheratan. Continue along the line between Sheratan to Mesarthim for about two or three binocular fields of view and you will get to Uranus. Return to this same spot for the next few nights. If the point you are looking at moves compared to the neighboring points of light, are are looking at Uranus.

Monday: The bright star Regulus is about two fingers to the right of the Moon at 8 p.m. They are three and a half fists above the east-southeast horizon.

Tuesday: Mars is three fists above the west horizon at 9:00 p.m.

Wednesday: 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 3:01 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 northern and southern celestial hemispheres (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.

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”.

Thursday: There is a lot to see at 6:30 a.m. The coffee pot. A hot shower. Your alarm clock. (Oh, I’m sorry. Apparently everyone uses their phone for an alarm now.) There is also a lot to see in the sky. The bright star Spica is less than one fist to the lower left of the Moon in the west-southwest sky. Jupiter is two fists above the south horizon. Saturn is one and a half fists above the south-southeast horizon. And bright Venus is a half a fist above the east-southeast horizon.

Friday: If you want to put somebody off, tell her or him to wait until Deneb sets. At Ellensburg’s latitude of 47 degrees, Deneb is a circumpolar star meaning it never goes below the horizon. At 9:42 p.m., it will be as close as it gets to the horizon, about two degrees above due north. Watch it reach this due north position about 4 minutes earlier each night.

The positional information in this column about stars and planets is typically accurate for the entire week. For up to date information about the night sky, go to https://nightsky.jpl.nasa.gov/planner.cfm.