Winter Stars And A Striking Comet-Star Cluster Pairing At Dawn

Orion already stands high in the southeastern sky just before dawn on Sept. 13. The Orion Nebula is the fuzzy spot in the short string of stars just below the belt. Bob King

With time off from work this week, I got up before dawn to stand face to face with Orion. What a beautiful thing the winter stars are on a warm, still September morning. Sometimes I like a little classical music when I’m out with the telescope, but the crickets and katydids outdid Mozart in their simple, insistent rhythms, so I turned the radio off this time.

The Orion Nebula is home to hundreds of newborn stars that form when clots of gas and dust contract under the force of gravity. NASA/ESA

At 4 a.m., one hour before the onset of morning twilight, Orion was already well up in the southeastern sky. He still leaned on his side, but the full figure of the Hunter stood out in the clear, bright stars throbbing in unseen air currents. I pointed the telescope to the pink rose that is the Orion Nebula. I’ve lost count of how many time I’ve looked at its bright folds and dark corridors shot with stars, but I keep coming back. It’s like being really thirsty and needing another glass of water.

In case you’ve never seen it the nebula is located just a few degrees directly below the belt in the middle of a short, perpendicular string of fainter stars. It’s about 1,345 light years away from Earth and 24 light years across. Vega, the brightest star in the Summer Triangle, lies 25 light years from our planet; next time you look up at that star imagine the Orion Nebula extending from the tip of your nose all the way to the star.

You can see the nebula faintly with the naked eye and discern its shape in binoculars, but through a telescope, especially an 8-inch or larger, it’s incredibly beautiful and still my favorite after all these years.

Tomorrow morning, comet 21p/Giacobini-Zinner passes over the bright star cluster M35 in Gemini. You can see them both in binoculars! To find the cluster, point your pair just shy of two fists to the upper left of Betelgeuse in Orion. Stellarium

From Orion I next took aim at comet 21P/Giacobini-Zinner in Gemini. It showed a delicate, 1°-long tail fanning to the west in my 15-inch reflector. The bright head of the comet, called a coma (Latin for “hair”), contained a tiny bright spot at its center, the nucleus of the comet. That’s where all the action starts. The nucleus proper is an irregularly-shaped object a mile or two across made primarily of water ice (plus dry ice, carbon monoxide ice and others) mixed with dust. When heated by the sun, the ices vaporize and carry away the dust. Pressure from sunlight “blows” the dust into a tail.

Comet 21P/Giacobini-Zinner shows a gossamer tail and bright nucleus in this photo taken on Sept. 9. The actual comet nucleus is hidden by dust, so we’re actually seeing what’s called the “false nucleus.” Gianluca Masi

The comet has an rare conjunction tomorrow morning with the bright star cluster M35 in Gemini. During the wee hours, it slowly travels across the cluster, passing just northeast of its center around 4 a.m. Central Time (5 a.m. Eastern, 3 a.m. Mountain and 2 a.m. Pacific) for the Americas. This will be  a unique opportunity to see the two right on top of the other through binoculars or a telescope. The comet will give the cluster a hazy look in binoculars, where a telescope will help you see both clearly.

Treat yourself to the sight and to the pleasure of the winter stars while the weather’s still pleasant.