This Week’s Sky at a Glance, July 14 – 21 ~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 200 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; M16, the Eagle Nebula; and star clusters such as M11, the Wild Duck Cluster in the constellation Scutum the Shield. 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 5:41 am and sunset will occur at 9:07 pm, giving 15 hours, 26 minutes of daylight (5:49 am and 9:09 pm in Saint John). Next Saturday the Sun will rise at 5:48 am and set at 9:01 pm, giving 15 hours, 13 minutes of daylight (5:56 am and 9:03 pm in Saint John).
The Moon is at first quarter on Thursday, making a great week for public observing events. It passes just above Mercury this Saturday evening, is near Venus on Monday and Jupiter next Friday. Jupiter’s red spot faces our way at 10 pm on Thursday and, under steady sky conditions, it can be seen with a telescope. Saturn continues to give great views of its rings in a telescope. Mars looks awesome in the late evening; its bright yellow-orange colour really catches the eye.
The annual RASC NB star party at Mount Carleton Provincial Park occurs July 13-14, taking advantage of very dark and moonless skies. Public observing events are also scheduled for Thursday, July 19, at the ball field in St. Martins for Old Home Week, and at the Irving Nature Park in Saint John on Friday, July 20 at 9 pm (cloud date Saturday, July 21).
Questions? Contact Curt Nason.