This Week’s Sky at a Glance, 2021 September 4 – 11
~by Curt Nason
The constellation Capricornus is a large chevron shape that is due south around 10 pm this week. A pair of stars marks each upper corner, and both stars of the western pair are colourful wide double stars. The sea goat arises from a tale of the Olympian gods being surprised by Typhon, the most ferocious of the rival Titans. Knowing Typhon was not fond of water, the gods changed into fish and escaped to the sea. The god Pan, who was half-goat and half-man, panicked and dove in before the transformation was complete and wound up with a goat’s head and the tail of a fish.
There are four common targets for backyard telescope users near Capricornus, but only the globular cluster M30 off the east side of the chevron is officially within its borders. It is also the easiest of the targets for binoculars. The globular cluster M72 and the four-star (literally four stars, it is not an observing highlight) asterism M73 are above in Aquarius. Nearby is the more challenging, but worth the effort, Saturn Nebula (NGC7009), the gaseous remnant of a dead star that somewhat resembles the ringed planet. Coincidentally, Saturn is currently in the western portion of the chevron and Jupiter is above the sea goat’s tail
A few millennia ago the Sun was in Capricornus at the winter solstice, when at midday it is overhead at its most southerly point at latitude -23.5 degrees. This is the southern border of the tropics, and it is still called the Tropic of Capricorn despite the Sun being in Sagittarius at this time. Earth’s 25,800 year polar wobble, called the precession of the equinox, is responsible for this shift.
This Week in the Solar System
Saturday’s sunrise in Moncton is at 6:43 am and sunset will occur at 7:51 pm, giving 13 hours, 8 minutes of daylight (6:49 am and 7:55 pm in Saint John). Next Saturday the Sun will rise at 6:52 am and set at 7:37 pm, giving 12 hours, 45 minutes of daylight (6:58 am and 7:42 pm in Saint John).
The Moon is new on Monday, appearing to the upper right of Mercury on Wednesday and Venus on Thursday. Mercury sets around 8:30 Wednesday, 45 minutes after sunset, followed by Venus nearly 40 minutes later. Also at midweek, Saturn is at its highest and best for observing by 11 pm and Jupiter at midnight. Jupiter’s Red Spot can be seen with a telescope around 11 pm Tuesday and near 8:30 on Friday. Beginning early in the week and extending over two weeks, rural observers might catch sight of the zodiacal light in the east 60-90 minutes before sunrise.
Questions? Contact Curt Nason at email@example.com.