Stellar Vista Observatory Sky Report
John Mosley
July 5 – 11
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 www.stellarvistaobservatory.org. Send questions and comments to [email protected].
This is the last week until late December that all five naked eye planets will be visible on the same night, so here’s where they are.
Venus and Mars are near each other low in the west in the evening sky. Venus is brilliant and you can’t miss it but Mars is only 1/200th as bright. Mars is to the upper left of Venus. Venus is moving toward Mars and their separation decreases dramatically day by day, so watch nightly with binoculars. On Monday, they’re 4 degrees apart but on Sunday, a scant degree apart, and they’ll be closest on the July 12 in a nice conjunction you don’t want to miss. Remember: a conjunction is a process, not a one-night event.
On Sunday evening, the ultra-thin crescent moon joins the pair. It’s only 4.5% illuminated by the sun and less than 5 degrees to the right of them ,and all three will fit in the field of view with binoculars. Notice that earthshine lights up the dark side of the moon; from the crescent moon the earth appears nearly full.
Venus is very slowly increasing its angular separation from the sun and it’s setting slightly later each night, but Mars is sinking lower and setting earlier. We’ll see Venus in the evening until the end of the year but Mars for only another month.
Jupiter and Saturn rise around midnight; Jupiter is the brightest star-like thing in the sky and much fainter Saturn is to Jupiter’s right.
Last visible is Mercury, very low in the east in morning twilight. Look an hour before sunrise through about the 13th, and it’s quite low. The crescent moon joins Mercury on Thursday morning when they’re 5 degrees apart. That morning the ultra-thin moon, which is just 2.4% illuminated, is only twice as bright as Mercury. The star near Mercury is Zeta in Taurus; you can watch Mercury move relative to the star.
The earth is farthest from the sun (aphelion) on July 5, when we’re 3.4% or 3 million miles farther than when we’re closest in January. It’s warm now because our northern hemisphere is tilted toward the sun. That we’re farther now makes our summers slightly cooler than they otherwise would be, but the effect is small. It’s just as well our planet’s orbit is so close to a perfect circle.