This Week’s Sky at a Glance, 2023 May 13 – May 20

This Week’s Sky at a Glance, 2023 May 13 – May 20

This Week’s Sky at a Glance, 2023 May 13 – May 20

This week stargazers have an opportunity to do an ISS marathon. The International Space Station orbits the earth at an altitude of about 400 km, and at this height it completes an orbit in approximately 90 minutes. The ISS has large solar panels that reflect sunlight earthward, which make it bright enough to rival Jupiter and Venus at times. Usually, we can catch it once or twice in morning twilight for a period of about ten days, then in the evening twilight for the same stretch, and then it is unseen for a while as the overhead passes are in daylight or shadow. For a month either side of the summer solstice, when we have long periods of twilight, the ISS can be seen four or five times from evening through to morning. If you see it in each pass throughout the night you have completed the ISS marathon.

To determine when and where to look I use the website Heavens-Above, but there are other apps such as Satellite Safari that give the same information and may even give you an alert when a pass is about to occur. Heavens-Above defaults to zero degrees latitude and longitude so be sure to enter your location. Information includes the date and time, brightness, and altitude and azimuth of when it is first visible (usually ten degrees above the horizon), at its highest, and when it disappears into earth’s shadow or below ten degrees. Brightness is given in stellar magnitude, where the lower the number the brighter is the object, and the ISS is usually bright enough to be a negative number (magnitude -3 is about 2.5 times brighter than -2). With the Heavens-Above website, clicking on the date brings up a sky map showing the path of the ISS through the constellations. Since earth rotates under the satellite, the path through the constellations will differ with each pass but it is always approximately west to east.

This Week in the Solar System

Saturday’s sunrise in Moncton is at 5:49 am and sunset will occur at 8:42 pm, giving 14 hours, 53 minutes of daylight (5:56 am and 8:44 pm in Saint John). Next Saturday the Sun will rise at 5:41 am and set at 8:50 pm, giving 15 hours, 9 minutes of daylight (5:49 am and 8:52 pm in Saint John).

The Moon is near Saturn this Saturday morning, and it is new next Friday. On Wednesday morning between approximately 8:56 and 9:56 the Moon passes in front of Jupiter. They will be almost halfway up the sky toward the southeast, with the Sun to the lower left so try to block it out with a tree or building. It will be a challenge to catch this in a telescope but lunar occultations of a planet are quite rare. Venus is making a move on Mars and it will be fun to watch this chase play out over the next few weeks. Jupiter rises 50 minutes before the Sun this weekend and could be visible with binoculars in twilight. Mercury rises more than 20 minutes later but it will likely be too dim to pick out until next month.

On Sunday evening at 8 pm, tune in to the Sunday Night Astronomy Show via the Facebook page or YouTube channel of Astronomy by the Bay.

Questions — Curt Nason


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