Star gazing
Dr. Rolly Chiasson’s “star” star this month is Capella.
Hi Sky Fans,
It’s time for another star month. Over the past several years, we’ve discussed Deneb – a summer star in Cygnus – the Swan; Aldebaran – an autumn star in Taurus the Bull; Fomalhaut – another autumn star in Pisces Austrinus.
This time our “star” star will be Capella. I used to sing about this star a cappella – ouch – that’s the poorest pun ever! Capella is a winter star. When I say winter, spring, summer, or autumn, I simply mean that particular star will be in the sky, in the mid-evening to early night – a convenient time to view, if it’s dark. If you stay up until the wee hours, you can see many stars not in the sky, in the evening, as the Earth rotates.
Look relatively high in the sky in the southwest. Capella us the highest bright star you can see in that direction. As March passes, it will be more and more westerly and somewhat lower.
Capella is the alpha, or brightest star, in the constellation Auriga the Charioteer. It is a circumpolar star for us – or almost. It just disappears below the horizon between June and August.
Capella translates to English as the “She Goat”. It is also know as the Goat star. Just below it are two dimmer stars known as the kids.
Capella is a binary star – that is two stars circling each other, but you can’t see this. It is the fourth brightest star viewed from 40 degrees north or greater (that’s us). Only Sirius, Vega, and Arturus are brighter, and the latter two only by a little bit. Problem – there are a lot of bright stars in winter, especially near Orion, so poor Capella hardly gets a break. I call Capella a winter star but that’s only when it’s highest. It’s really a three-season star.
If we look back 210,000 years, Capella was actually the brightest star in our sky, because it was significantly closer to our solar system.
Of all the really bright stars in our sky, Capella is the only one that has a yellow colour – like our own sun. So go out and find Capella, and follow it through three seasons of the year. Now, what’s in the sky during March? As always, first our planets.
Evening – Jupiter now dominates. It rises at mid evening now and is highest after midnight. Look south then.
Venus is still with us and still bright but it is closer and closer to sunset and will disappear later this month. On the 25th we have inferior conjunction when Venus passes between us and the sun. We can’t see it. Mercury passes on the other side of the sun sway from us on March 6 and we can start to see it low in the west in the evening sky by March 20.
Mars is still in our evening sky still to the upper left of Venus and much dimmer. It’s been in the same place in the sky – just about – since October 2016 but that will change. Morning – Saturn begins the month by showing itself at about 2:30 a.m. in the east and rises earlier as the month progresses.
Late in the month, Venus again joins us, now in the a.m. in the east.
In late March, the comet Tuttle-Giacobin-Kresak, will pass through the Big Dipper. It may be naked-eye visible. It returns every 54 years, but most years are not particularly good. This year is an exception. Spring begins on March 20 this year. This is the time of year when the day’s length changes most quickly – by about four minutes on that day. After that, the amount of change each day begins to slow.