Saturday: Tonight’s full moon is in the constellation Sagittarius. The Wishram, Haida, and Tlingit people of the Pacific Northwest call the July full moon the salmon moon. This is the time of year the salmon return after spawning season.
Sunday: Mercury 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 Mercury is in the evening sky, it is east of the Sun so this occurrence is called the greatest eastern elongation. This evening will be the best evening to observe Mercury for the next few weeks. Mercury is nearly a half a fist held upright and at arm’s length above the western horizon at 9:20 p.m. Over the next few weeks, Mercury will move toward the Sun in the sky. By late August, it will be visible in the morning sky.
Monday: Zubenelgenubi, the second brightest star in the constellation Libra. The name means "southern claw", a holdover from the time when this part of the sky was associated with the neighboring constellation of Scorpius the scorpion. Zubenelgenubi is a binary star system, easily seen with binoculars as a white and yellow pair. To a person living on a planet orbiting the dimmer of the two stars, the brighter star would be nearly as bright as the full Moon appears from Earth. Zubenelgenubi is one and a half fists above due southwest at 10:30 p.m.
Tuesday: Saturn is about a fist to the left at 11:30 p.m., about a fist above the east-southeastern horizon.
Wednesday: What you see with the naked eye isn’t all that can be seen. While astronomers can learn a lot from observing the sky in the visible wavelengths, many celestial objects radiate more light, and more information, in wavelengths such as radio, microwave, infrared, ultraviolet, x-ray, and gamma ray. In 2012, NASA launched the Wide-field Infrared Survey Explorer (WISE) to study objects that radiate in the infrared range such as asteroids, cool dim stars, and luminous galaxies. For an interesting comparison of how different wavelengths show different aspects of celestial objects, go to http://goo.gl/nvuax. If it weren’t for infrared telescopes such as WISE, astronomers would not know about the significant amount of dust in galaxies. We also wouldn’t know how much brighter than the Sun red supergiant stars are. Antares is a red supergiant star, currently sitting at one and a half fists above the southern horizon at 9:30 p.m. In the visible wavelengths, Antares shines 10,000 times brighter than the Sun. But since Antares is much cooler than the Sun, its energy distribution peaks in the infrared. So across all wavelengths of light, Antares shines 60,000 times brighter than the Sun. The new James Webb Space telescope is also an infrared telescope.
Thursday: At 4:30 a.m., Jupiter, the brightest point light in the sky at this time, is about two and a half fists above the eastern horizon. Mars is a half a fist to the upper right of Jupiter.
Friday: Let’s learn about Capella. It is the fourth brightest star we can see in Ellensburg. It is the most northerly bright star. It is a binary star consisting of two yellow giant stars that orbit each other every 100 days. At 10:00 p.m., Capella is less than a half a fist above due north. You can also use the Big Dipper to find it. First, find the two “cap” stars on the cup of the Big Dipper, the stars on the top of the cup. Draw a line from the “cap” star closest to the handle to the cap star farthest from the handle. Then, continue that line to the next very bright star, which is Capella. Thus, you can “cap” to Capella. If you can’t “cap” tonight, don’t worry. Capella is the brightest circumpolar star meaning it is the brightest star that never goes below the horizon from our point of view in Ellensburg.
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.
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