Southern Summer Skies

Facing South in the Summer

Facing south in the summer reveals a rich region of the night sky featuring the heart of the Milky Way and several excellent zodiac constellations. If you have a clear horizon to the south, the constellation Scorpius dominates the space with a long curving shape that winds around the horizon back to the tip of the tail of the scorpion, a feature called the Cat's Eyes, Shaula and Lesath.

For the next few months, Saturn is lurking next to the head of the scorpion, adding a bright highlight to the pattern. Scorpius and neighboring Sagittarius (to the east) are found directly in the center of the galaxy so there are numerous deep space objects to be found in the vicinity, making it one of the best places to enjoy with binoculars. You can move from spot to spot and never run out of interesting objects to see. This week the gibbous Moon drifts through that region of the sky so the darkness will be somewhat spoiled, but I find it good to get to know constellations when there is moonlight as well as when you have complete darkness. With moonlight you can learn the basic outline of the constellation, and without moonlight the deeper objects will emerge and reveal themselves to the careful viewer.

Image courtesy Sky & Telescope. 

Red 'Stars' and White Moon

Slender Moon, Mars and more

For the next week, the twilight sky will feature a close alignment of two bright shiny red objects, Mars and Antares, and the slender Moon wending its way through the southwestern sky. The Moon encounters the ringed planet Saturn on Saturday 27th and then brackets the close pairing of orange-red Mars and the red supergiant star Antares in the constellation Scorpius. This first lunar cycle of autumn should start out beautifully with the waxing Moon and some lovely alignments. Look south and west shortly after sunset each evening for the best viewing.

Image courtesy Sky & Telescope.

Old Moon at Dawn

Old Moon at Dawn

The early morning sky this week features an old Moon fading each day into the sunrise, passing landmarks in our sky as it fades. The Moon follows a path across the sky that parallels the planets, so there are frequent encounters between the Moon and planets, and on the 25^th that features the planet Saturn, not positioned in the east before sunrise. Saturn is gradually moving from the constellation Libra into Scorpius over the next few years, but the Moon makes that same move across the sky in a few days, passing by the bright orange heart of the Scorpion, Antares, one of the biggest stars in the entire galaxy.

You will need a good eastern horizon to see the fullness of Scorpius and the Moon’s path on the 26^th and 27^th but if you are up early you will have a treat seeing these bright objects shining in the morning darkness.

The Galactic Center: Staring Into the Heart of the Milky Way

Summer is prime time to look into the heavens and touch the wonder of the Galactic Center, the heart of our own Milky Way galaxy. Two bright constellations guide you to the center of the Milky Way, Scorpius and Sagittarius, which are easy to spot due south each evening shortly after sunset.

The Galactic Center

Our own Sun and Solar System occupy their special place 30,000 light years from the center of the Milky Way, and as we look out and around us into space, we view our own galaxy from within, along the spiral arms and toward the center. Many have seen the lovely band of the Milky Way when camping or far away from city lights, but the faint river of light is all but invisible in any urban area. Nonetheless, with binoculars, you can see deeper into the sky and discover some of the deep space wonders and faint objects that are visible between our own location and the center of the galaxy, an area full of star clusters and nebulae. So I encourage everyone to get a pair of binoculars, face south, and using the star chart (above) as a guide, aim between Scorpius and Sagittarius and meander from there upwards. You will encounter the Lagoon Nebula and the nearby Trifid Nebula, easily visible in city lights if you use a telescope or binoculars, and many more Messier Objects, the fuzzy blobs that dot the sky near the Galactic Center.

In six months, when the Earth has traveled half-way around the Sun, we'll be able to look in the opposite direction, toward the Galactic Anticenter, as I have described in a previous blog post. That is interesting to consider, but more exciting is the Summer when we can enjoy our own galaxy's finest wonders on full display.

Here's a link to an image of the Galactic Center on Sky & Telescope's website.

Image courtesy SkySafari.

Seeing Summer in Winter - Scorpius and Sagittarius

The early morning sky this week holds some treasures for star gazers. As the view of the heavens changes from season to season, we have a chance to see the symmetry of our sky by looking south-east in the morning. In winter, we see the majestic winter sky in the evening, but by early morning we see the summer sky! How is this possible? Every 12 hours as the Earth rotates on its axis, we face the different constellations and in fact see the "opposite" season in the morning. This week, as the old Moon passes through the summer constellations of Scorpius and Sagittarius, it accentuates the rich beauty of these two constellations, both of which contain many treasures for the unaided eye as well as for those who wish to get out their binoculars for a closer look.

Sagittarius is located in same direction as the center of the Milky Way, and Scorpius is just next to this, so both contain a richness of nebulae and star clusters that are easy to find in binoculars. It's worth the extra 2 minutes in the morning to take a look if you can get outside before the first light of dawn, before 6:00 am in San Francisco.

Celestial Companions in the Cold Dark Morning

January mornings are dark times, and when the sky is clear it is certain to be chilly outside. So I find the sight of the old Moon reassuring, a warm light that fades a bit each successive morning and guides the way through bright stars and planets along the ecliptic to the soon-to-be-rising-Sun. You can see this spectacle at its finest the next few mornings as the Moon moves a bit further eastward each day and passes near to some distinct celestial companions.

The Moon is passing now through Scorpius and the grey-white of the Moon stands in stark contrast to the red-orange of the star at the heart of the Scorpion, Antares. Moving close to Antares on Friday morning, the Moon continues toward the brilliant planet Venus on Saturday morning, and then slowly fades into the glare of sunrise on Sunday morning. My kitchen window faces south-east so I see this changing landscape each morning and I look forward to the coming days with clear skies in the forecast. If you rise before sunrise, take a moment to look out toward the south-east and enjoy the calm of this morning celestial grouping of close companions in the heavens.

KFOG Podcast - September 10, 2010

Another fun visit with Irish Greg of the KFOG Morning Show, today featuring a discussion of constellations to see this time of year (Sagittarius, Scorpius, The Summer Triangle) and the difference between an asterism and a constellation, plus deep-space objects you can see in the Milky Way with an ordinary pair of binoculars. And the latest happenings with the Moon and Venus, and an update on a great star party and lecture this weekend. All in 7 short minutes! Click here to listen.

High in the sky: The Big Dipper

The Big Dipper is one of the easiest groupings of stars in the sky to identify, and it serves as a guide to some of the more interesting stars in other parts of the sky. Late Spring evenings it is nearly overhead as seen from San Francisco, and its distinctive pattern provides an interesting exercise for understanding the motions of objects in the heavens.

The Big Dipper is not a constellation, by strict definition, because it is only the brightest 7 stars of the larger constellation Ursa Major. A named combination of stars within a constellation such as the Big Dipper is known as an "asterism." Because of its distinctive shape, the Big Dipper is a very well known asterism, one of several celestial groupings that lives up to its name (I put Leo, Scorpius, Cygnus and a few other constellations in this special class).

The Big Dipper points to the North Star (Polaris) if you follow the two stars at the side of the bowl of the dipper. This Wikipedia article illustrates this nicely. The line along the pointers from the Big Dipper to Polaris is helpful because this line is similar to an hour hand on a 24-hour clock. Every 24 hours the Big Dipper makes one counter-clockwise rotation around Polaris. From latitude 38 degrees north (approximately the latitude here in San Francisco) the Big Dipper is high in the sky when it is above Polaris (as it is now at sunset) and low in the sky when it is rotated half way around Polaris just above the horizon (as it will be in late Fall evenings).

The three stars in the handle of the Big Dipper form a curve, and if you think of this curve as an arc, you can follow it to a very bright star called Arcturus (in the constellation Bootes), and by continuing along this arc you end up at another bright star called Spica (in the constellation Virgo).

One more fun thing to find in the Big Dipper is the middle star of the handle, known as Mizar. This star has a very close companion, Alcor, next to it and if you want to test your eyesight, see if you can split the two without using binoculars or a telescope.

Enjoy learning about the Big Dipper in the pleasant weather of May and June. It's full of surprises and one of my favorite stops when sharing the sky with friends and guests at star parties.

The Milky Way and the Galactic Center

At the SFAA star party a couple nights ago on Mt Tam, the conditions were very clear and dark and we had a nice view of the Milky Way. With an excellent southern horizon, we could see all of Scorpius and Sagittarius and as my daughter and I were giving star tours to guests at the star party, I was happy to point out these two constellations and note that the center of the Milky Way was in the vicinity of the tail of Scorpius and the "teapot" of Sagittarius. This is called the "Galactic Center" and is the central bulge of the Milky Way Galaxy.

Looking toward the galactic center, however, you don't see a huge ball of light. That is because there is a massive dust cloud that lies between the Sun and the galactic center. Too bad for us, because it would be quite amazing to see the center of our own galaxy. Nonetheless, there is much richness in the sky near the galactic center and even in city lights you can begin to see some of that beauty if you use a pair of binoculars. Standard 7x35 or 10x50 binoculars can substantially increase the amount of light you can see, and that means you can begin to discern the stars and shapes of deep space objects such as the Lagoon Nebula or the Swan Nebula. Take out binoculars and point yourself south and see if you can start to see some of the wonders that are at the heart of the Milky Way.

Scorpius now in view

The summer constellation Scorpius is now center-stage in the southern sky. It's always a treat to see the distinctive shape of Scorpius with red supergiant star Antares glowing in the sky. Through binoculars Scorpius is great because of an abundance of deep-sky objects in and near the constellation. And this week there is an extra treat as the moon passes through.