Minnesota Starwatch is a newsletter describing the night sky in the Midwest.
Updated monthly, it is produced by the
Minnesota Starwatch for July 2015
by Deane Morrison
July opens with Venus and Jupiter forming a close pair low in the west after sunset. As usual, Venus outshines Jupiter.
The two planets took months to get together, and now they uncouple and sink into the sun's afterglow. Relatively sluggish Jupiter drops because Earth is leaving it behind in the orbital race, but our sister planet is speedier than Earth and has plans of its own. In the second half of July, Venus dives into the sunset as it hurtles toward its next passage between Earth and the sun. By month's end, both planets will be all but lost in the sun's glare.
Try looking for the planets about 50 minutes after sunset on the 18th, when a young crescent moon appears with them. You may even spot Regulus, the brightest star in Leo, above Venus. Binoculars will help.
July evenings are great for enjoying Scorpius and the Teapot of Sagittarius. Sinuous Scorpius rears up from the south, extending its claws westward toward Libra while the scorpion's red heart, Antares, glows softly. As a bonus, Saturn shines above the claws. Just east of Scorpius, the spout of the Teapot is poised to pour its contents onto the scorpion's tail. Moving east again, we see the handle of the Teapot and the little Teaspoon of stars hanging above it.
This year July has two full moons. The first comes at 9:20 p.m. on the 1st and rises, round and beautiful, approximately half an hour before sunset. The second arrives at 5:43 a.m. on the 31st; look for it in the west around 5:30 a.m. The second full moon in a calendar month is sometimes called a blue moon. The term was originally used to mean the third of four full moons in a season, but the two-in-one-month phenomenon is easier to notice and celebrate.
For another morning treat, look eastward before the sky starts to lighten on the 12th to see a waning crescent moon near Aldebaran, the eye of Taurus, along with the lovely Hyades and Pleiades star clusters.
On the 14th, NASA's New Horizons spacecraft will perform a flyby of Pluto and its five associated bodies. Pluto was the Roman god of the underworld, and though it has been demoted from planet to dwarf planet status, Pluto turns out to have quite a retinue. Its large companion, Charon, was the boatman who ferried souls across the river Styx into the underworld. Four small moons have also been found: Styx; Nix (named for the mother of Charon); Kerberos, the Greek form of the name of the dog that guarded the underworld; and Hydra, named for the nine-headed serpent that Hercules had to kill.
Pluto is now among the stars of the Teaspoon. We can't see it, but when New Horizons sends back images we'll have our first close-up view of this distant and mysterious corner of the solar system.
Duluth, Marshall W. Alworth Planetarium: www.d.umn.edu/planet
Twin Cities, Minnesota Institute for Astrophysics (during fall and spring semesters): www.astro.umn.edu/outreach/pubnight
Check out the astronomy programs at the University of Minnesota's Bell Museum ExploraDome: www.bellmuseum.umn.edu/ForGroups/ExploraDome/index.htm
06/23/15 Contact: Deane Morrison, University Relations, (612) 624-2346,
Find U of M astronomers and links to the world of astronomy at http://www.astro.umn.edu.