Sky at a Glance 2021 July 17 – 24

This Week’s Sky at a Glance, 2021 July 17 – 24 ~by Curt Nason

Serpens the Serpent is unique among the 88 constellations in that it is split in two by another constellation, Ophiuchus. As the name suggests, Ophiuchus is the Serpent Bearer, and he is often depicted holding a large snake. The two constellations are also intertwined in mythology.

Ophiuchus represents Asclepius, a renowned healer who could raise the dead. After killing a snake one day, he watched as another snake placed an herb on its dead companion and revived it. After this, Asclepius learned the healing arts and his success at reviving people drew the ire of Hades, a brother of Zeus and ruler of the Underworld. Receiving a complaint from Hades that he was being robbed of subjects, Zeus killed Asclepius with a thunderbolt.

The part of Serpens west of Ophiuchus is called Serpens Caput (meaning head); to the east is Serpens Cauda (for tail). M16, the Eagle Nebula, is a rather faint nebula with a star cluster in Serpens Cauda. It gained fame as the iconic Pillars of Creation photo from the early years of the Hubble Space Telescope. The delightful globular cluster M5 is found in Serpens Caput, and several other globular clusters reside within the borders of Ophiuchus.

This Week in the Solar System

Saturday’s sunrise in Moncton is at 5:45 am and sunset will occur at 9:05 pm, giving 15 hours, 20 minutes of daylight (5:53 am and 9:07 pm in Saint John). Next Saturday the Sun will rise at 5:52 am and set at 8:58 pm, giving 15 hours, 6 minutes of daylight (6:00 am and 9:00 pm in Saint John).

The Moon is at first quarter this Saturday morning, and it is full next Friday evening as it nears Saturn. Venus passes near Leo’s lucida, Regulus, on Wednesday, presaging a closer but less brilliant pairing of Mars and Regulus the following week. Jupiter and Saturn are attracting attention in late evening to the southeast, with both coming to opposition next month. On Monday telescope users can catch Jupiter’s moon Io disappear into the planet’s shadow around 11:30 pm, and 80 minutes later Europa will emerge from behind the opposite side. These events are called an eclipse disappearance and an occultation reappearance. This weekend Mercury rises 75 minutes before sunrise, and by next weekend the gap shortens to 50 minutes.

Questions? Contact Curt Nason.

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