Thursday, October 19, 2023

The Ellensburg, WA sky for the week of October 21, 2023

Saturday: The Orionid meteor shower consists of the Earth colliding with pieces of the remains of Halley's Comet's tail. This shower peaks after midnight tonight and tomorrow night. This is not a meteor shower that typically results in a meteor storm. There will be about 15-20 meteors per hour, many more meteors than are visible on a typical night but not the storm that some showers bring. The Moon is near the first quarter phase, meaning it will set around midnight. The best time to observe will be near dawn. Meteor showers are named after the constellation from which the meteors appear to originate. These meteors appear to come from a point in Orion, the hunter. This point is about one fist held upright and at arm’s length above due east at midnight. You can follow this point throughout the night as it will remain one fist above the prominent reddish star Betelgeuse (pronounced Bet'-el-jews). The Orionid meteors are fast - up to 40 miles per second. If you fall asleep tonight, you can catch the tail end of the shower every night until early November. For more information, go to https://earthsky.org/?p=27937.

Sunday: At 9:00 p.m., Saturn is three fists above due south and Jupiter is two and a half fists above the eastern horizon.

Monday: Venus will be as far away from the Sun in the sky as it will get this orbital cycle. This "farthest away" point is known as the planet's greatest elongation. Since Venus is in the morning sky, it is west of the Sun and this occurrence is called the greatest western elongation. This morning, Venus is three fists above the east-southeastern horizon at 6:30 a.m. Over the next few months, Venus will move toward the Sun in the sky. By next summer, it will be visible in the evening sky.

Tuesday: Halloween is a week from today so make sure you load up on peanut clusters, almond clusters, and open star clusters this week. That last one will be easy (and cheap… actually free) because two of the most prominent open star clusters in the sky are easily visible in the autumn sky. The sideways V-shaped Hyades Cluster is two fists above due east at 10:00 p.m. Containing over 300 stars; the Hyades cluster is about 150 light years away and 625 million years old. The Pleiades Cluster is a little more than three fists above due east. It has three times as many stars as the Hyades Cluster and is younger. Compared to our 5 billion year old Sun, the 100 million year age of the Pleiades is infant-like.

Wednesday: What time is tea time? Certainly not during an autumn evening. The constellation Sagittarius the archer, with its signature teapot shape, is sinking into the southwestern horizon by 8:00 p.m. The handle is on top and the spout is touching the horizon ready to pour that last cup of tea.

Thursday: Fomalhaut is one and a half fists above the southern horizon at 9:30 p.m.

Friday: Halloween weekend is a great time to celebrate the dead. Dead stars, that is. Black holes are and neutron stars are the end result of super massive stars. But intermediate mass stars such as our Sun end up as white dwarfs. After fusing hydrogen into helium for most of its life and fusing helium into heavier elements for a relatively short period at the end of its life, the Sun will end up with a core of carbon and oxygen that no longer produces energy through nuclear fusion. Without the outward radiation pressure from fusion resisting the inward pull of gravity, the Sun will end up as a super-dense sphere of atoms in which the electrons are squished onto the nuclei. It will be an object with nearly all of its mid-life mass but in a volume about the size of the Earth. The easiest white dwarf to see is in the triple star system called Keid, from the Arabic word “qayd” meaning egg shells. Learn more about Keid, also called 40 Eridani, including map of how to find it at

https://www.skyandtelescope.com/observing/trick-or-treat-with-white-dwarfs/. At midnight (scary), Keid is a little more than two fists above due southeast. You’ll need a small telescope to see it. First find Rigel, the brightest star in the constellation Orion. It is one and a half fists above the east-southeastern horizon. Then use binoculars to find the right area. With Rigel at the bottom of your field of view. There should be a star near the top of your girls of view that is about one sixth as bright. This star is called Cursa. Next, move your binoculars up and to the right about one and a half field of view diameters. Look for two stars close together, each about one third as bright as Cursa. Finally, move your binoculars straight over to the right about one and a half field of view diameters. The lower of these two stars is Keid or 40 Eridani A. You’ll need a telescope to see the white dwarf, called 40 Eridani B.

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.

No comments: