This Week’s Sky at a Glance, 2023 July 22 – July 29
This Week’s Sky at a Glance, 2023 July 22 – July 29
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 and blur 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 of them 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 several 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 5:49 am and sunset will occur at 9:00 pm, giving 15 hours, 11 minutes of daylight (5:57 am and 9:03 pm in Saint John). Next Saturday the Sun will rise at 5:57 am and set at 8:53 pm, giving 14 hours, 56 minutes of daylight (6:05 am and 8:55 pm in Saint John).
The Moon is at first quarter on Tuesday, providing great views in a telescope all week. This weekend Mercury is a fist-width to the right of Venus, and by next Friday it will be half that distance above Venus and very close to Regulus. Mars is upper left of Venus this weekend, setting 45 minutes later. By midweek Saturn rises around 10:30 pm and Jupiter rises before 1 am. The minor South Delta Aquariid meteor shower peaks next weekend.
Upcoming public observing includes one for the Perseid meteor shower at the Irving Nature Park in Saint John on August 11, and the Mount Carleton Star Party on the weekend of August 18-19.