Get Involved: Dark Skies

As an Urban Astronomer, I am enthusiastic about astronomy even in the light-polluted urban centers of the world, including my own city of San Francisco. I write this blog for many reasons, one of which is to remind city dwellers that there is still plenty to see in the night sky. Right here in San Francisco, there are ways to view the sky in a dark spot, away from streetlights and brightly-lit areas of the City, and see quite a bit of the night sky. Mainly you just need patience to let your eyes dark adapt your location, and before you know it you can find quite a few stars and constellations.

Over the past weeks, I was traveling in and around Flagstaff, AZ, the World's First International Dark Sky City. Flagstaff is a medium-size city of about 60,000 people, but through smart street lighting, has reduced its light output considerably. While visiting Lowell Observatory on a hill above Flagstaff, you could see the city lights below, but it was not like any other I had seen. Clearly there was light from the city, but it was subdued, not shining up in the sky but rather shining down onto the streets and public spaces. That is Smart Lighting!

There is a global organization called the International Dark-Sky Association that provides advocacy and education to support communities and municipalities around the world to learn about smart lighting and preservation of dark skies. I applaud their efforts and their mission. Locally in San Francisco fellow SFAA member Dave Goggin has organized a list and invites participation in San Francisco discussions about lighting.

What can you do in your community to preserve dark skies? I am sure the Dark Sky Association would welcome your participation. It's a very grass roots thing. Here is an article about an individual in San Clemente starting a movement there. Get inspired!

Jupiter, Venus and the Moon grace the Evening Sky

The Moon, Venus and Jupiter, the three most dominant objects in the night sky, will form a number of beautiful patters to grace the evening sky in the coming days. Venus and Jupiter have become so dominant in the west after sunset each night that you cannot help but notice them shining like diamonds, and as we enter a new lunar cycle, the young Moon creates beautiful patterns as the daily change in relative position makes for an exciting night sky. Things will get even more exciting next month when Venus and Jupiter reach conjunction, when they are at their closest alignment.

Image courtesy of Sky & Telescope Magazine.

Auriga and Capella: the Galactic Anticenter

High overhead in the winter sky is the distinctive constellation Auriga the Charioteer. This is a bright constellation, visible even with city lights, punctuated by the 6th brightest star in the night sky, Capella. To the casual viewer, Auriga appears to be a pentagon in the sky, and in winter it is nearly directly overhead as night sets in. Depending upon the source, the constellation Auriga is described as the actual Charioteer holding a goat, or just the shape of his pointed  helmet. The star name Capella is in fact Latin for 'small goat.'

Auriga has the distinction of being located in the direction of the Galactic Anticenter. What is an anticenter? It is the point in the night sky that is opposite the Galactic Center, of course :-)  The center of the Milky Way Galaxy is located in the direction of the constellation Sagittarius, a dominant summertime constellation. So not surprising, in the winter time when we are looking the 'other direction' in the sky, we find ourselves staring out into space directly out of our Milky Way Galaxy.

The bright star Capella is relatively close to Earth, 42 light years away. It shines brightly in the winter sky, making Auriga easy to locate. A fascinating fact is that the star Capella is not one star, but a four-star system made up of two binary stars. That means, that the four stars are broken into two pairs of binary star systems. Two of them are big stars, 10 times the size of our Sun. The other two are quite small and faint, so when you see Capella you are primarily seeing the two bigger stars. Some binary star systems can be seen as separate stars in small telescopes or binoculars, but the two bigger stars in the Capella system are too close to see as separate objects.

Try to locate Auriga and Capella tonight and savor the fact that you are staring out of the Milky Way into the vastness of space far away from our home galaxy.