The Ellensburg, WA sky for the week of June 22, 2024

Saturday: “Mom, I can’t sleep. It is too light out!” A poor excuse you say. Good astronomy skills, I say. The latest sunset of the year happens around this date. Surprisingly, the earliest sunrise and the latest sunset do not both happen on the longest day of the year, the day of the summer solstice. The earliest sunrise occurs just before the longest day and the latest sunset occurs just after the longest day. This phenomenon relates to the angle of the Sun’s path near rising and setting. In Ellensburg, that angle is about 66 degrees above the southern horizon at noon near the first day of summer. Because of the Earth’s orbit, which causes the Sun’s apparent motion, the angles are not symmetric. The asymmetry in orbital angles leads to the asymmetry in rise and set times. This year, the sun sets at about 9:01 p.m. every night this week as viewed from Ellensburg, WA. Find sunset data for your location at https://www.timeanddate.com/.

Sunday: I hope that you have never been in a collision. It can be scary and dangerous. The biggest collision in our celestial neighborhood will occur in a few billion years when our Milky Way Galaxy will collide with the Andromeda Galaxy. Here’s a simulation of what it will look like: https://svs.gsfc.nasa.gov/30955. If you can’t stay awake for a few billion years to see the collision, stay up until late at night to see the Andromeda Galaxy. First find the Great Square of Pegasus. At 2:00 a.m., the left-hand corner of the square is about three fists above the east-northeastern horizon. Less than two fists to the left and down a little bit is another star the same brightness as the star at the corner of the square. From that star, hop about a half a fist up to a star that is about one fourth as bright. Less than another half fist in the same direction is a fuzzy oval patch of light known as the Andromeda Galaxy. The galaxy is a little over three fists above the northeastern horizon. The galaxy is impressive to see in binoculars. It consists of nearly a trillion stars and is 2.2 million light years away.

Monday: In 1982, the British group Bow Wow Wow first sang, “I Want Candy”. In May 2019, NASA finally granted that wish by releasing images of Mars’ moon Phobos looking like candy. The thermal imaging camera on NASA’s long lived Odyssey orbiter took a series of images of the full phase of Phobos. The resulting composite, looking like a many layered jawbreaker, shows how the temperature varies throughout the small moon. This temperature distribution, in turn, can help astronomers determine what the moon is made of. For more about this yummy treat, go to https://www.jpl.nasa.gov/news/why-this-martian-full-moon-looks-like-candy. Mars is one and a half fists above the eastern horizon at 4:00 a.m.

Tuesday: Mercury is the only planet visible in the evening sky this week. It is a little less than a half a fist above the west-northwestern horizon at 9:30 p.m.

Wednesday: Don’t wait until next week to watch those wimpy firecracker shows. Find the hypergiant star Rho Cassiopeiae. Astronomers think that Rho Cassiopeiae will likely go supernova (explode) soon. Of course, for stars, “soon” might mean today. It might mean 20,000 years from now. Rho Cassiopeiae is in the constellation Cassiopeia the queen. At 11:00 tonight, Cassiopeia looks like the letter “W” about two and a half fists above the north-northeastern horizon. Rho Cassiopeiae is about a finger’s width to the right of the rightmost star in the “W.” Once you find it, you’ll be thinking, “Big deal, I can hardly see it.” Although it is barely visible to the naked eye, it is actually very bright. It is the 20th most luminous star in the sky, a whopping 550,000 times more luminous than the Sun.

Thursday: Did you know that you can see a few bright planets and stars during the day? It really helps if they are close to an easy to spot object such as the Moon. Saturn is near the Moon in the sky from sunrise until moonset a little before noon. At sunrise, Saturn is to the upper left of the Moon. At moonset, Saturn is to the lower right of the Moon. They are closest in the sky at 9:00 a.m., when the Moon is about two fists above the southwestern horizon. First find the Moon with binoculars. Saturn will be visible less than a Moon radius to the upper right of the Moon. Lower your binoculars while looking at the Moon and Saturn. You may still be able to see Saturn with the naked eye now that you know exactly where it is located.

Friday: Happy Asteroid Day (http://www.asteroidday.org/), the day we celebrate avoiding the destruction of the Earth by an undiscovered asteroid. There are about a million asteroids in the Solar System with the potential to strike Earth and destroy a city. Astronomers have discovered only 1% of them. Asteroid Day is an effort to educate the public and encourage policy makers to fund this important effort. King Tut may have celebrated an ancient Asteroid Day by asking his assistants to make a dagger out of a broken-off asteroid that landed on Earth. Astronomers discovered that the blade of the knife contained much more nickel than is found in terrestrial iron, an amount consistent with iron meteorites, especially with one found in the year 2000 in the Kharga region in northern Egypt. For more information about the dagger, go to http://goo.gl/BHBivd.

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. All times are Pacific Time unless noted.