Spring is here! Well at least astronomically speaking as March 20th marks the Vernal Equinox, so while we still have wintry weather with snow, spring now has officially sprung. Here is your guide to the sky for March 20 to 26, 2017…
Sun – Earth – Moon
Monday, March 20 at 6:29 am marks the Vernal Equinox, the first day of Spring in astronomical terms. Equinox means “equal night” meaning the length of daylight and darkness are approximately equal in length. No matter where you live on Earth, the Sun will appear to rise due east and set due west on your horizon this day. At both equinoxes (Vernal and Autumnal), the Sun appears overhead at noon as seen from Earth’s equator. The Sun is on the celestial equator which intersects all of our horizons at points which is why we see the rising and setting points on these days directly east and west. Of course while it is the Vernal Equinox for us marking the first day of Spring in the Northern Hemisphere, remember it is the Autumnal Equinox for the Southern Hemisphere and they officially begin the Fall or Autumn season there. This equinox (Vernal or Spring one) was very important in a variety of cultures who relied on agriculture. Persians celebrate No Ruz on this day and it was marking their New Year. In Japan people use this day to remember their ancestors. Many cultures celebrate planting on this day Sunrise this week is at 6:32 am and sunset at 6:52 pm. The Moon is at Last Quarter on Monday night as well and will pass three degrees south of the planet Saturn that morning.
Dance of the Planets
Mercury is gaining height in our evening sky in the western sky but you will need a good horizon to catch it. Venus might be visible on Monday or Tuesday, but after that it is lost in the glare of sunset. It reaches inferior conjunction on Saturday. In a week or so it will re-emerge in the pre-dawn sky. Reddish Mars is visible until around 10:00 pm while Jupiter rises around 8:10 pm east. Saturn rises in the eastern sky around 2:00 am for you early risers. The ringed jewel is a wonderful sight in small telescopes!
Constellations – Chasing a bear
The Big Dipper also known as Ursa Major (the great bear) rises high into our Spring evening skies, and last week we used it to find Leo the Lion. Now let’s use it to find Bootes the Herdsman (bear chaser) in the sky. You will want to wait until around 9:00 pm or so. Go out and find the Big Dipper and follow the handle to make an “arc” to the bright star Arcturus in Bootes. Arcturus is a reddish-orange giant star with a diameter 25 times that of our Sun and it emits about 100 times as much visible light. It is roughly 37 light years distant from our Sun. Arcturus is at the bottom of a kite or cone-shape group of stars marking Bootes who in Greek mythology was a herdsman or shepard who guarded his flocks from the bear and used his cane to chase it away. Most people today think it looks like an ice cream cone or maybe a kite – either way it is a clear sign that spring is here when it is in the eastern sky shortly after sunset. The constellation will continue to get higher in the sky as spring progresses.
Satellites to see
Monday evening look for the Resurs 01 Rocket (a Russian natural resources satellite) from 7:27 to 7:36 pm moving from southeast to north. Wednesday morning find ISS from 5:41 to 5:44 am moving from west to South. Saturday try finding the Lacrosse 5 Rocket from 8:26 to 8:31 am moving from northwest to east. Sunday evening look for ISS from 7:45 to 7:46 making a low grazing pass in the southeastern sky.
As spring arrives, I hope Bootes chases the winter weather away and gives us clear spring skies for evening viewing. Warming weather will be here soon and as the constellations change with the seasons, there is always something to new to see by looking up. Happy stargazing and keep your eye on the sky!