Sky at a Glance 2022 April 23 – 30

Photo showing the planet Mercury next to the Pleiades in Taurus during the last week of April.

This Week’s Sky at a Glance, 2022 April 23 – 30 ~by Curt Nason

When people see a telescope that doesn’t look like it came from a department store, they often ask how far you can see with it. The answer is difficult to explain and even more difficult to comprehend. Sometimes I just say “way far” and hope they don’t press for details.

This weekend the brightest object before sunrise will be the Moon and it is about 375,000 kilometres away, a little less than its average distance. The next brightest object is Venus, currently 140 million kilometres and receding. Mars is 250 million km away, Jupiter 860 million, and Saturn 1.5 billion km out there. Light travels at 300,000 km per second, so at 150 million km the Sun is a distance of 500 light seconds away. The Moon is a tad more than one light second away; Jupiter is 48 light minutes and Saturn about 84 light minutes.

The brightest star we see in the evening now is still Sirius, the closest star we can see from New Brunswick at 8.6 light years (ly). The next brightest is Arcturus and it is 37 ly or 350 trillion kilometres. Polaris, the North Star, is about 400 ly away; and Alnilam, the middle star of Orion’s belt, is 2000 light years. If you are under a dark sky well before morning twilight you might get a naked eye glimpse of the Andromeda Galaxy at a distance of 2.5 million light years. Binoculars will reveal galaxies even more distant, but at what point do these distances become incomprehensible and “way far” is a reasonable answer?

This Week in the Solar System

Saturday’s sunrise in Moncton is at 6:18 am and sunset will occur at 8:17 pm, giving 13 hours, 59 minutes of daylight (6:25 am and 8:20 pm in Saint John). Next Saturday the Sun will rise at 6:07 am and set at 8:26 pm, giving 14 hours, 19 minutes of daylight (6:14 am and 8:29 pm in Saint John).

The Moon is at third quarter this Saturday and new next Saturday. On Monday morning it makes a squashed triangle with Saturn and Mars, and on Wednesday it makes a much tighter triangle with Venus and Jupiter. Over the week early risers can watch Mars increase its distance from Saturn by 50%. Unseen by us, Venus has an extremely close conjunction with Neptune Wednesday afternoon, but we can easily watch it close the gap with Jupiter by next weekend. At midday April 30, Venus will be a moon-width below Jupiter near the southwest. Mercury will be within a binocular view of the Pleiades from Tuesday on throughout the week, passing closely to the left of the dipper-shaped star cluster next Saturday, one day after its greatest elongation from the Sun.

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? Contact Curt Nason.

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