What's up in the Ellensburg, WA sky for the week of June 24, 2023

Saturday: Nearly 400 years ago, Galileo looked at the Pleiades star cluster through his telescope and noticed that the seven or so stars in the region visible to the naked eye became many more. There are two main types of star clusters. Open star clusters, like the Pleiades and the Beehive, are groups of a few dozen to a few thousand stars that formed from the same cloud of gas and dust within our galaxy. Stars in open star clusters are young as far as stars go. Globular clusters are groups of up to a few million stars that orbit the core of spiral galaxies such as our own Milky Way. One of the most well known star clusters is the globular cluster in Hercules, an object that is fairly easy to find with binoculars. First find Vega, the bright bluish star five and a half fists held upright and at arm’s length above the eastern horizon at 11:00 p.m. Two fists above Vega, and close to straight overhead, is a keystone shape. Aim your binoculars at the upper left hand star of the keystone, the star closest to straight overhead. The globular cluster is one third of the way to the rightmost star of the keystone. It looks like a fuzzy patch on the obtuse angle of a small obtuse triangle. If you don’t know what an obtuse angle is, you should not have told your teacher, “I’ll never need to know this stuff”.

Sunday: Venus is about a fist above the west-northwestern horizon at 10:00 p.m. Mars is about a thumb width to the upper left of Venus.

Monday: Spica is about a half a fist to the lower left of the moon in the southwestern sky at 10:00 p.m.

Tuesday: 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) in the near future. Of course, for stars, “near future” 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.

Wednesday: Hot enough for you? If not, astronomers using NASA’s Spitzer Space telescope have discovered a planet so hot that molecules can’t even remain intact. This planet, called KELT-9b, is an ultra-hot Jupiter with a surface temperature of 7,800 degrees Fahrenheit. Hydrogen gas molecules are ripped apart on the hot day side and recombine on the much cooler night side. For more information about this discovery, go to https://exoplanets.nasa.gov/news/1626/for-hottest-planet-a-major-meltdown-study-shows/.

Thursday: Saturn is just above the east-southeastern horizon at midnight. By 4:00 a.m., Saturn is three fists above the south-southeastern horizon and Jupiter is two fists above due east.

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.