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Find Antares in the heart of Scorpius

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Friday, July 13, 2018 8:51 PM

Greetings, Stargazers.

The 416 Fire has made it challenging for many of us to get outside to see the night sky. I have enjoyed breathing clean air again this week. Now that the smoke has been replaced by evening monsoon clouds, we may miss some stargazing activities, but the moisture is most welcome.

Due south at 10 p.m., you will see the reddish star Antares. It is the heart of Scorpius, one of my favorite constellations. I like it because it is one of the very few constellations that looks to me just like what its name says it should. The front of the scorpion is above and to the right of Antares, and the tail curves down to the left toward the horizon, ending in a pair of stars for the stinger. The tail is very near the brightest part of the Milky Way.

The name Antares means rival of Mars. Most of the time, it might be a rival, but this summer, there is not much of a rivalry, as Mars is exceptionally bright. This is one of the times every few years when Mars is even brighter than Jupiter. At magnitude -2.56, Mars is more than 25 times brighter than Antares, which is magnitude 1.03.

There are several mythological stories about the scorpion, and most involve Orion. In one version, the scorpion stung and killed Orion but was then stepped on and killed by Orion as he died. These mortal enemies were then placed on opposite sides of the heavens so they would never be in the sky at the same time.

Slightly more than 1 degree to the west of Antares is the globular cluster M4. Because of its proximity to Antares, it is one of the easiest globulars to find. It should be visible in binoculars as a tiny puff ball, and telescopes will reveal a dense, spherical cluster.

To the east of the scorpion’s stinger is the open cluster M7. It is visible to the naked eye as a faint, fuzzy patch, and binoculars will show a nice, rich grouping of stars.

This monthTonight (Saturday), the crescent moon will be just above the planet Mercury in the western sky right after sunset. The very bright planet Venus is about 15 degrees above and to the left of the moon.

Since the moon moves about 13 degrees through the sky every day, on Sunday night, it will be very close to Venus.

Jupiter, slightly less bright than Venus, is just more than 30 degrees above the horizon to the south. The orientation of Jupiter is still such that the Galilean moons will periodically transit in front of Jupiter, or be eclipsed by them. You can see the moons with binoculars, but you would need a telescope to see any details of a transit.

Saturn is still near the teapot asterism of Sagittarius and will be up at dusk, about 25 degrees to the east of Antares.

Mars is rising in the southeastern sky a bit before 10 p.m. It reaches opposition, its closest approach to Earth, on July 27, so there should be good views all month.

You may have seen, as I have, shares on social media that July 27 brings another total lunar eclipse. That is true, but we are on the wrong side of the world to see it. Unless you are planning a really long trip this month, your next chance to see one will be in January.

Charles Hakes teaches in the Physics and Engineering Department at Fort Lewis College and is the director of the Fort Lewis Observatory. Reach him at hakes_c@fortlewis.edu.

Useful links

Size and distance to the planets: https://bit.ly/2M2oOEK
Astronomy picture of the day: http://apod.nasa.gov/apod/
An astronomer’s forecast for Durango: https://bit.ly/2eXWa64
Old Fort Lewis Observatory: www.fortlewis.edu/observatory
Four Corners Stargazers:
https://bit.ly/2eUqRJXhttps://bit.ly/2iGQPTbhttps://bit.ly/2igOSMc

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