This Week’s Sky at a Glance, 2019 June 29 – July 6 ~by Curt Nason
Five millennia ago, Persian and perhaps Egyptian astrologers designated four of the first magnitude stars (the 20 brightest) as Watchers of the Sky, with each guarding one of the four cardinal directions. With their proximity to the Sun at the equinoxes and solstices they were also used to mark seasonal changes. Collectively, they were known as the Royal Stars.
Regulus in Leo and Antares in Scorpius were two of the Royal Stars, and we see them now appearing through evening twilight. Regulus guarded the north and marked the summer solstice, while Antares guarded the west and marked the beginning of autumn. Fomalhaut, in Piscis Austrinus below Aquarius, guarded the south and marked the winter solstice. Aldebaran, currently rising in Taurus less than an hour before sunrise, guarded the east and marked the spring equinox. These stars no longer mark the seasons as they did 5000 years ago due to precession of Earth’s polar axis, which makes one complete wobble every 25,800 years. On the summer solstice, the Sun is now located near the border of Gemini and Taurus.
None of the Royal Stars make the top ten in brightness. The brightest star in the sky for this time of year, Arcturus, is at its highest at sunset. It precedes almost equally bright Vega, which anchors the Summer Triangle with Deneb and Altair. Vega reaches its highest point about half an hour before Fomalhaut rises around 2:30 am. These two stars are the same distance from us, at 25 light years.
This Week in the Solar System
Saturday’s sunrise in Moncton is at 5:30 am and sunset will occur at 9:14 pm, giving 15 hours, 44 minutes of daylight (5:39 am and 9:16 pm in Saint John). Next Saturday the Sun will rise at 5:35 am and set at 9:12 pm, giving 15 hours, 37 minutes of daylight (5:43 am and 9:14 pm in Saint John). Earth is at aphelion on Thursday, its farthest distance from the Sun for the year at 152.1 million kilometres.
The Moon is new on Tuesday, with a very slim crescent forming a triangle with Mercury and Mars on Wednesday after sunset. Jupiter is at its highest and best for observing around midnight, and telescope users might see its Red Spot around 11 pm this Saturday. Saturn is high enough around midnight to give decent views of its magnificent icy rings. Venus can be seen with difficulty in morning twilight, rising 45 minutes before sunrise.
The next RASC NB star party will be at Mactaquac Provincial Park on July 5 – 6. The Saint John Astronomy Club meets at the Rockwood Park Interpretative Centre at 7 pm on July 6. All are welcome.
Questions? Contact Curt Nason.