The Ellensburg, WA sky for the week of May 22, 2021

Saturday: In 1979, the group Foreigner recorded the song “Head Games”. They could have been singing about the constellations Hercules and Ophiuchus when they said “head games, it’s just you and me baby, head games, I can’t take it anymore” because the heads of these two constellations have been right next to each other in the nighttime sky for all of human history. And just to make it easy for you, a star that bears an Arabic name that means “the head” represents each head. In Hercules, it's Ras Algethi (head of the kneeler); in Ophiuchus, Ras Alhague (head of the serpent charmer). At 11:00 p.m., Ras Alhague, the brighter of the two, is nearly three and a half fists held  above the east-southeastern horizon. Ras Algethi is about a half a fist to the upper right of Ras Alhague.

Sunday: Antares is a half a fist above the southeastern horizon at 10:00 p.m.

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 jaw-breaker, 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/news.php?feature=7398. Mars is two fists above the western horizon at 10:00 p.m. 

Tuesday: Venus and Mercury are close together in the early evening sky for the next few nights. At 9:00 p.m., Mercury is less than a fist to the upper left of Venus, about one fist above the west-northwestern horizon.

Wednesday: There is a total lunar eclipse tonight. What could be better than that? A supermoon total lunar eclipse. The Moon is near perigee meaning it is near its closest to Earth. Total lunar eclipses are not as noticeable as total solar eclipses because light still reaches the Moon even when it is completely blocked by the Earth. That is because the Earth’s atmosphere acts like a lens and bends rays of light toward the Moon that would normally miss the Moon. However, that doesn’t mean the Moon looks the same during a total lunar eclipse as it does during a normal full moon.

Sunlight is white. White light is the sum of all of the colors in the visible spectrum (red, orange, yellow, green, blue, indigo and violet). Our atmosphere scatters the blue component of the Sun’s white light. That is why our sky is blue. (If our atmosphere consisted of different gasses, we would likely have a different colored sky.) When the Sun or Moon is near the horizon, the light passes through a lot of the atmosphere meaning a lot of the blue light is scattered and the Sun or Moon looks redder than when it is high in the sky. During a total lunar eclipse, sunlight passes through a large slice of the Earth’s atmosphere. The remaining light that reaches the Moon is reddish. Some people say the fully eclipsed Moon looks Blood Red! These people exaggerate. It arrears a dull reddish color.

From our perspective in Ellensburg, Washington, Pacific Time Zone, the partial eclipse stage will start at 2:45 a.m. The Moon will slowly move into the Earth’s shadow and get dark from left to right. At 4:11 a.m., the Moon will be fully eclipsed. The total eclipse lasts until 4:26 a.m. Soon after this, the Moon will set. Thus, during the entire eclipse, the moon looks white, then black, then red all over. For more information about the eclipse, including information about the specific times for your location, go to https://www.timeanddate.com/eclipse/lunar/2021-may-26.

Thursday: Since you got up early yesterday to watch the lunar eclipse, why not get up early to see Jupiter and Saturn. At 4:30 a.m., Jupiter is more than two fists above the southeastern horizon while Saturn is nearly two fists to the  right of Jupiter. Unless you are a robot or an alien, you are looking at the visible wavelengths coming from Jupiter. In addition to visible wavelengths, there are telescopes that observe Jupiter in ultraviolet and infrared wavelengths. Studying multiple wavelengths will teach you a lot more about an object just like studying multiple languages will teach you more about a culture. For example, Jupiter's Great Red spot looks larger in the infrared image. NSF’s NOIR Lab has published an article that allows you to easily compare the three wavelength views of Jupiter. Go to https://noirlab.edu/public/news/noirlab2116/. Es muy bueno.

Friday: Mercury and Venus are in “conjunction” tonight, one fist above the west-northwestern horizon at 9:00 p.m. I put “conjunction” in quotes because it makes me appear too important to take the time to look up a better word. Strictly speaking, two objects are in conjunction when they are at the same sky longitude, called Right Ascension. From the point of view of Ellensburg, that will happen when the two planets are below the horizon. But they are closest together in the sky tonight, right after sunset. Mercury is just to the lower left of Venus, so close that you may not be able to fit your pinky between them. Before going outside, type the following url with your pinky and read about the conjunction: https://earthsky.org/?p=356424. 

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.