This Week’s Sky at a Glance, 2019 July 27 – August 3 ~by Curt Nason
Stargazers prefer meridian observing because that is when we should have our best views of objects in a telescope or binoculars. The meridian is the imaginary line running from north to south, separating the sky into eastern and western hemispheres. When stars and planets cross the meridian they are at their highest, shining through a minimal thickness of atmosphere en route to our eyes. Unstable pockets of atmosphere will distort the light from stars and planets, blurring the view; so minimal atmosphere means less distortion. Astronomers use the term “seeing” to describe the steadiness of the atmosphere. Good seeing means steady air and we can use higher magnification for observing details of the Moon and planets.
Around 10 pm this week we have several prominent constellations near the meridian. Moving southward from the North Star we have Ursa Minor or the Little Dipper. A small telescope with good seeing conditions will show the close companion star of Polaris, which is actually a triple star although only two can be seen in a telescope. Heading southward we pass through Draco the Dragon on our way to Hercules. The faintest of the four stars in the dragon’s head is an easy double star to resolve in binoculars. The globular cluster M92 is about halfway between the head and the Keystone asterism of Hercules, and don’t forget M13 along the western side of the Keystone.
Hercules goes head-to-head with Ophiuchus to its south, which contains a few globular clusters itself. Ophiuchus stands on Scorpius, keeping the scorpion underfoot so that it cannot fatally sting Orion again. Scorpius at the meridian is the best time to observe globular clusters M4 and M80, and open clusters M6 and M7.
This Week in the Solar System
Saturday’s sunrise in Moncton is at 5:55 am and sunset will occur at 8:55 pm, giving 15 hours of daylight (6:02 am and 8:57 pm in Saint John). Next Saturday the Sun will rise at 6:03 am and set at 8:46 pm, giving 14 hours, 43 minutes of daylight (6:10 am and 8:49 pm in Saint John).
The Moon is new around midnight Wednesday evening, and appears as a slim crescent in the west after sunset by Friday. Jupiter is at its highest and best for observing after twilight, and telescope users might see its Red Spot around 10 pm on Sunday and 11:30 pm on Tuesday. Saturn is near the meridian around midnight. Late in the week Mercury will be rising an hour before sunrise. The South Delta Aquariid meteor shower will be at its best two hours before sunrise on Sunday and Monday mornings, but the radiant does not rise very high in the south.
The annual star party at Mount Carleton Provincial Park takes place on August 2-3, and the Saint John Astronomy Club meets in the Rockwood Park Interpretative Centre on August 3 at 7 pm. All are welcome.
Questions? Contact Curt Nason.