This Week’s Sky at a Glance, 2020 July 11 – 18 ~by Curt Nason
Galaxies are favourite targets for amateur astronomers and many are visible with just binoculars. Two are easily seen with the naked eye in the southern hemisphere: the Large and Small Magellanic Clouds. The Andromeda Galaxy is a naked-eye blur for rural New Brunswickers and it looks majestic in binoculars. But there is one galaxy that is spectacular regardless of your location or observing equipment, and that is our home galaxy.
The Milky Way is at least 110,000 light years across, and although it is composed of perhaps 400 billion stars we can distinguish only about 4000 as individual stars from a rural area. The Sun is 27,000 light years from the galactic core, within a spur between the inner Sagittarius and outer Perseus spiral arms. When we look above the spout of the Sagittarius Teapot asterism we are looking toward the galactic core, but vast clouds of dust hide the stars between the spiral arm and the core. South of the head of Cygnus the Swan we see the Milky Way split in two by the Great Rift, one of those dust clouds.
Star formation occurs in clouds of gas and dust within the spiral arms and some can be seen as bright patches with binoculars. Just above the spout of the Teapot is M8, the Lagoon Nebula; and a hint of M20, the Trifid Nebula, can be seen in the same field of view above. Scanning to the upper left up the Milky Way you encounter M17, the Swan (or Omega) Nebula; and star clusters M16 in the Eagle Nebula and M11, the Wild Duck Cluster. A tour of the Milky Way under a dark sky can keep a binocular stargazer engaged for an evening.
This Week in the Solar System
Saturday’s sunrise in Moncton is at 5:39 am and sunset will occur at 9:09 pm, giving 15 hours, 30 minutes of daylight (5:47 am and 9:11 pm in Saint John). Next Saturday the Sun will rise at 5:46 am and set at 9:04 pm, giving 15 hours, 18 minutes of daylight (5:54 am and 9:06 pm in Saint John).
The Moon is at third quarter Sunday, passing near Mars this Saturday and near Venus next Friday. Brilliant Venus is in the Hyades star cluster near Aldebaran this weekend, with Mercury far to its lower left rising 50 minutes before the Sun. Jupiter is at opposition on Tuesday, rising at sunset. Its moon Io emerges from the planet’s shadow at 10:27 pm Thursday, while the Red Spot might be seen in a telescope around 10 pm on Friday. Nearby, Saturn’s rings are open a generous 22 degrees for telescope viewers. Mars rises before 12:30 am this week, slowly appearing bigger and brighter as it moves toward a spectacular opposition in October. Comet C/2020 F3 NEOWISE is circumpolar this weekend, meaning it is far enough northward that it doesn’t set, and it moves from Auriga to the front paws of Ursa Major over the week. It has been seen with the naked eye and looks spectacular in binoculars, if the sky is clear.
With astronomy meetings and outreach activities on hold, you can watch the local Sunday Night Astronomy Show at 8 pm and view archived shows.
Questions? Contact Curt Nason.