May 17

Sky Report: May 17 – May 23

Saturn Nebula, courtesy Fort Lewis College Observatory

This is the final week that all five planets are visible. Mercury is low in the west after sunset, where it has been all month, but this week it leaves us.

A few weeks ago Mercury was on the far side of the sun and approaching us in a big arc. On the 27th it’s as far from the sun as it will be, angle-wise, and that’s 22°. Then it’s coming straight at us and telescopically it looks like a tiny half-moon. As it continues to approach, it grows larger and becomes an ever-slimmer crescent – and grows fainter — until it’s between the us and the sun on June 9th. On what day will you last see it? Incentive will be strong on the 28th, and more on that next week.

Look for Mercury low in the west a half-hour after sunset, and use binoculars because the sky is still so bright. If your horizon is low enough you’ll see Venus, which is much brighter, below Mercury. Venus is getting easier to see night-by-night while Mercury is getting harder.

Mars is 1/3 of the way up the western sky one hour after sunset, in the middle of the Gemini Twins. The stars Castor and Pollux, which are slightly brighter, are above Mars, while substantially brighter stars are Capella to the right and Procyon to the left. We’ll see Mars until early July.

In the morning sky, brilliant Jupiter rises 4 hours before the sun. An hour before sunrise — when the sky is beginning to brighten — Jupiter is 1/3 of the way up the southeastern sky where it outshines everything else.

Saturn is to the upper right of Jupiter, and they’re separated by 17°, almost twice the width of your fist held at arm’s length. Watch this separation increase in years to come. Saturn is 3 magnitudes or 15X fainter than Jupiter.

If you have a telescope note that the planet Saturn is closer to the Saturn Nebula than it will be for the next 30 years. Saturn is a planet with rings that orbits our sun; the Saturn nebula is a shell of gas expelled by a star at its center; the star has become a white dwarf. It lies roughly 3,000 light years away, is magnitude 8, and superficially resembles the planet Saturn which is 6° below. Any of the astronomy apps I’ve recommended will let you find it.

The Sky Report is presented as a public service by the Stellar Vista Observatory, a nonprofit organization based in Kanab, Utah, which provides opportunities for people to observe, appreciate, and comprehend our starry night sky. Additional information is at Send questions and comments to

About the Author:

John Mosley
John Mosley was Program Supervisor of the Griffith Observatory in Los Angeles for 27 years and is the author of “Stargazing for Beginners” and “Stargazing with Binoculars and Telescopes”. He and his wife live in St. George where he continues to stargaze from his retirement home while serving on the advisory committee for Stellar Vista Observatory.

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