This Week’s Sky at a Glance, 2020 May 9 – 16 ~by Curt Nason
Comets are my favourite observing target and the fact that they can be tantalizingly coy and unpredictable only adds to their allure. Famed comet discoverer David Levy compared them to cats, in that they have tails and do exactly what they want. Once or twice a decade one will be bright enough to be seen easily without optical aid, and one or two a year might be reasonable targets with binoculars. Several can be within reach of a medium size telescope each year, depending on the size of the scope and on the darkness of your sky. It is not unusual to have months elapse with no comets to target.
Currently we have a three plus comets within reach of a telescope under good conditions, three more teasingly near the Sun, and a potential naked eye one on our doorstep. I say three plus because one has broken apart and two of the pieces are seen as comets, although fading quickly. All three are within the sparse constellation Camelopardalis the Giraffe, between the two Dippers (Big and Little) and Auriga, and the dearth of bright stars to guide you makes locating them a challenge. I prefer to use the maps on the Heavens Above website to locate comets.
The three in Camelopardalis are 2017 T2 Pan-STARRS, 2019 Y1 ATLAS, and 2019 Y4 ATLAS (and Y4-A) . I saw all three one evening in mid-March from a reasonably dark-sky site with my 8-inch telescope, and two of them from my backyard last month. The names derive from the year of discovery, the half-month of discovery (I and Z are not used), and the person(s) or robotic telescope program that made the discovery. Of the above, two were discovered in the latter half of December 2019 by the ATLAS program which, like Pan-STARRS, is searching for potentially hazardous asteroids. Comet 2020 F8 SWAN is currently a binocular object in southern hemisphere twilight and will be near bright Capella in Auriga by the end of this month. It could be seen with binoculars in twilight or, as it rounds the Sun a few days before, it could become a naked-eye object or break up and disappear. Such are comets.
This Week in the Solar System
Saturday’s sunrise in Moncton is at 5:53 am and sunset will occur at 8:38 pm, giving 14 hours, 45 minutes of daylight (6:01 am and 8:41 pm in Saint John). Next Saturday the Sun will rise at 5:45 am and set at 8:46 pm, giving 15 hours, 1 minute of daylight (5:52 am and 8:49 pm in Saint John).
The Moon is below Jupiter on Tuesday, reaches third quarter on Thursday, and it is lower left of Mars on Friday. Saturn and Jupiter reach their stationary points this week, on Monday and Thursday, respectively. For the next four months they will be in retrograde motion, separating slowly while moving westward relative to the distant stars. This weekend Mars crosses the constellation border into Aquarius. Needing a rest, Venus is also stationary on Wednesday before plummeting sunward over the next few weeks. By midweek, Mercury will be setting an hour after sunset.
With astronomy meetings and outreach activities on hold, you can catch the local Sunday Night Astronomy Show at 8 pm and view archives of previous shows.
Questions? Contact Curt Nason.