The Ellensburg, WA sky for the week of December 7, 2019

What's up in the sky 12/7/19

Today:  The CWU Physics Department and the College of the Sciences is hosting its monthly First Saturday planetarium show today from noon to 1 p.m. Do you ever wonder how to find objects in the sky? Or how to explain to someone else where you have found something? CWU student and future teacher Grace Warren will answer these questions in her show called “How to measure the sky: Gittin’ griddy wit it”. The show is free and open to all ages. There will be a show at noon on the first Saturday of every month of the school year hosted by different CWU astronomers and astronomy educators. The CWU Lydig Planetarium is room 101 in Science Phase II, just off the corner of 11th and Wildcat Way, H-11 on the campus map found at https://www.cwu.edu/facility/campus-map.

Sunday: Jupiter is about to be lost in the glare of the Sun. Look for it today at 4:45 p.m., less than half a fist above the southwestern horizon. Venus and Saturn are to the upper left of Jupiter, about one fist above the horizon. Venus is the brightest of the three planets.

Monday: Oh no. Mercury is about to be lost in the glare of the Sun, as well. At 6:30 a.m., Mercury is less than a half a fist above the southeastern horizon. Mars is one and a half fists above due southeast.

Tuesday: The earliest sunset of the year in Ellensburg occurs today and tomorrow: 4:12 p.m. This seems odd because the shortest day of the year, the winter solstice, isn’t for about two more weeks. The Sun is at its southernmost point with respect to the background stars on the day of the winter solstice. This means the Sun spends the least amount of time above the horizon on that day. But, the sunrise and sunset times depend on more than the Sun’s apparent southward motion in the sky. It also depends on where the Sun is on the analemma, that skinny figure-8 you see on globes and world maps. During the second week in December, the Sun is not quite to the bottom of the analemma. But, it is on the leading edge of the analemma, the first section to go below the horizon. For a slightly better explanation of this, including a diagram, go to https://go.shr.lc/2NOMOQC. Or just go watch the sunset. But don’t stare at the Sun. 

Wednesday: It’s getting too cold to see frogs in the wild. Some people see them on their dinner plate. But this is a great time to see frogs in the sky. Ancient Arabs referred to the stars that we now call Fomalhaut and Diphda as Ad-difdi al-awwal and Ad-difda at-tani. This means the first frog and the second frog, respectively. Both frogs are low in the southern sky at 5:30 p.m. Fomalhaut is nearly one and a half fists above due south. The slightly dimmer Diphda is two fists above the south-southeast horizon.

Thursday: The bright star Capella is nearly straight overhead at midnight.

Friday: The Geminid meteor shower peaks tonight and tomorrow morning. Meteor showers are named after the constellation from which the meteors appear to originate. These meteors appear to come from a point in Gemini the twins. This point is about four fists above due east horizon at midnight tonight. You can follow this point throughout the night, as it will remain near the bright star Castor, the right hand star of the “twin” stars Pollux and Castor. By 4 am, it is four fists above the southwest horizon. This shower is typically one of the best ones of the year producing bright, medium speed meteors with up to 80 meteors per hour under ideal conditions near the peak. This year is not ideal because the waning gibbous Moon is also in Gemini so it will follow the meteor shower for the entire night.

Most meteor showers occur when the Earth passes through the orbital trail of a comet. The broken off comet fragments collide with the Earth and burn up in the atmosphere. Astronomers had searched for a comet source for this shower since 1862 when the shower was first observed. Finally, in 1983, astronomers discovered the object that created the fragments that cause the meteor shower. To their surprise, it was a dark, rock that looked like an asteroid, not a shiny icy comet. Astronomers named this object Asteroid 3200 Phaethon. For more information about the Geminid shower, go to https://goo.gl/f4qMqg. 

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.