Sky at a Glance 2020 April 25 – May 2

Photo showing closeup of Orion and the Moon in the eye of Taurus with Venus above.

This Week’s Sky at a Glance, 2020 April 25 – May 2
~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.

On a clear evening this week just go outside and look up. The brightest object will be the Moon and this weekend it is about 395,000 kilometres away. Next weekend it will be near perigee at 360,000 km. The next brightest object is Venus, which will be at inferior conjunction on June 3 and hence closest to us at a distance of 43 million kilometres. In the morning sky, Mars is currently 180 million km away, Jupiter 720 million, and Saturn is 1.6 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 40 light minutes and Saturn about 80 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 km. Polaris, the North Star, is about 400 ly away; and Alnilam, the middle star of Orion’s belt, is 2000 ly, 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. A small telescope will reveal things 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 6:14 am and sunset will occur at 8:20 pm, giving 14 hours, 6 minutes of daylight (6:21 am and 8:23 pm in Saint John). Next Saturday the Sun will rise at 6:03 am and set at 8:29 pm, giving 14 hours, 26 minutes of daylight (6:10 am and 8:32 pm in Saint John).

This Saturday (April 25) the Moon occults a star that forms one eye of Taurus the Bull, within a half hour of setting. Around 10 pm find a location with a good western horizon and use binoculars to watch the sinking Moon creep toward the star and, around 10:30, make it disappear. The Moon is near Venus on Sunday and the next evening it passes near the M35 star cluster in Gemini. On Wednesday, the day before first quarter phase, telescope users can see the Lunar X forming on mountaintops just inside the shadow line during late evening. On Tuesday Venus is at its greatest illumination, which occurs approximately five weeks before and after it reaches inferior conjunction. By next weekend Mars will have moved to 20 degrees east of Saturn, while Saturn and brighter Jupiter remain within 5 degrees, the field of view of most 10×50 binoculars.

Monday marks the beginning of International Astronomy Week, but this year the outreach events will be online. You can catch the local Sunday Night Astronomy Show at 8 pm and view archives of previous shows.

Questions? Contact Curt Nason.

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