Taking Out the Trash Tonight?

Check out the Sky While You’re At It

Sometimes people think that you have to set aside hours and hours to do stargazing. It ain’t so! Some evenings you can take a big bite in a short time, what I like to think of as “Big Gulp” stargazing. Last night when I went to put the trash out, I stood there and took in the crescent Moon and Venus low in the western sky. Over in the southwest, Orion was doing his thing, and high overhead Saturn glittered in Gemini. Jupiter was hanging there in the East. Lots of stuff to take in on just one quick trip out with the trash cans! Now, if you want to try it, take along a pair of binoculars and check out the planets or the Orion Nebula. Tonight (Tuesday, Feb. 24), the crescent Moon, Mars, and Venus will all be lined up low in the west after sunset. Wednesday night, the Moon and Mars will be very close together. It’s a free star show, and all you have to do is step outside after sunset and look up! (And hope it isn’t cloudy.)

It’s Dark Out There!

Yesterday there was a news conference at NASA about something called “dark energy.” What is this stuff? Well, strictly speaking it’s not matter. It’s a force. We’re all familiar with the force of gravity, which acts to hold things together, particularly at the atomic level. Across huge distances — and I’m talking big ones, like between galaxies and clusters of galaxies (what astronomers like to refer to as “cosmic” distances”), gravity is part of a complex dance that warps galaxies that pass too close and keeps members of a cluster more or less together. Important stuff, this gravity. We all know that the universe has been expanding since the Big Bang, about 13.7 billion years ago. Everybody just assumed that gravity would have some effect on this cosmic expansion, maybe even slow it down.

Such a gravitational braking force would affect light from distant objects, and people who study shifts in the wavelengths of light from very distant stellar explosions called Type Ia supernovae though that they’d see the slowing effect of gravity in the spectra (the minute details of the light) of the supernovae. Turns out they didn’t. In fact, what they DID find is that the expansion of the universe is speeding up! Something is accelerating the expansion and this speed-up started about 5 billion years ago — roughly about the time our Sun and planets were forming.

That “push apart” force is called “dark energy.” It’s a lousy name for a factor that Albert Einstein postulated way back in the early years of the 20th century. He couldn’t believe it existed and so he discarded it. In retrospect that doesn’t look like a good move on Einstein’s part, but hey — you have to admit it does seem a little strange to have something mysterious out there pushing the galaxies apart faster than gravity can hold them together.

Now, this dark energy doesn’t act on something as small as our planet or you and me — like gravity at cosmic scales, it acts across cosmic distances. So, I wouldn’t worry too much about the solar system flying apart or the Milky Way doing something brash like sending the Orion Arm on over to Andromeda for a friendly visit. It doesn’t work that way. The full extent of dark energy’s influence will echo across time for another 30 billion years or so, if it continues pushing at its presence pace.

It’s not really a big thing to worry about personally, but as part of the puzzle that is our universe — and while we understand much about the cosmos, we certainly don’t have a handle on all of it — it certainly does pose a tantalizing new piece for scientists to chew over as they push the limits of our telescopes back to the earliest epochs of history. Keep your ears open for more on this dark energy stuff — and don’t believe anybody who tells you it’s a fantastic new source of energy for perpetual-motion machine. That’s woo-woo territory…

A short programming note: I’d like to direct your attention to the link I added for Gemini Observatory over in my links column on the left. I’ve been doing some work with the fine folks there and I thought you might like to see some of the good astronomy they’ve been doing with their telescopes at Mauna Kea and Cerro Pachón in Chile. Give ‘em a visit and see what’s new at Gemini!

A Rose From Space

This Spitzer Space Telescope image of a stellar nursery was obtained with an infrared array camera sensitive to invisible infrared light at wavelengths that are about ten times longer than visible light. In this four-color composite, emission at 3.6 microns is depicted in blue, 4.5 microns in green, 5.8 microns in orange, and 8.0 microns in red. The image covers a region that is about one quarter the size of the full moon.

This is kind of cool. The folks at Spitzer Space Telescope have caught onto the “positive PR spin” thing pretty well and have issued a lovely picture of a rosebud-shaped stellar nursery called NGC 7129. Smack in the middle of the bud is a cluster of newborn stars, and all of this loveliness lies about 3,300 light-years away in the constellation Cepheus. There are about 130 young stars here, all formed from a huge cloud of gas and dust.

Here’s what the Spitzer folks have to say about their discovery:

“As in any nursery, mayhem reigns. Within the astronomically brief period of a million years, the stars have managed to blow a large, irregular bubble in the molecular cloud that once enveloped them like a cocoon. The rosy pink hue is produced by glowing dust grains on the surface of the bubble being heated by the intense light from the embedded young stars. Upon absorbing ultraviolet and visible-light photons produced by the stars, the surrounding dust grains are heated and re-emit the energy at the longer infrared wavelengths observed by Spitzer. The reddish colors trace the distribution of molecular material thought to be rich in hydrocarbons.

The cold molecular cloud outside the bubble is mostly invisible in these images. However, three very young stars near the center of the image are sending jets of supersonic gas into the cloud. The impact of these jets heats molecules of carbon monoxide in the cloud, producing the intricate green nebulosity that forms the stem of the rosebud.

Not all stars are formed in clusters. Away from the main nebula and its young cluster are two smaller nebulae, to the left and bottom of the central “rosebud,” each containing a stellar nursery with only a few young stars.

Astronomers believe that our own Sun may have formed billions of years ago in a cluster similar to NGC 7129. Once the radiation from new cluster stars destroys the surrounding placental material, the stars begin to slowly drift apart. “

Happy Valentine’s Day!