Stargazing in October

What’s Up and Happening in our Skies

Now that we’ve all enjoyed (if we could last week) the lunar eclipse, there’s a partial solar eclipse coming up next week that will be visible to at least some observers around the world on October 23rd. It’s partial because the Sun will only be partially blocked, which means that it’s not an eclipse you can watch with the naked eye. In fact, it is REQUIRED that you wear eye protection or use special projection methods to observe this eclipse. Although it should go without saying, I’m going to say it anyway: NEVER LOOK AT THE SUN WITHOUT EYE PROTECTION!  Practice safe solar viewing. Use eclipse glasses, welder’s glass, or use pinhole projection to see this event.

It begins at 3:38 p.m. EDT (7:38 PM UT). It sets eclipsed for most viewers.  If you live in North America or the extreme eastern parts of Asia, you have a shot at observing the eclipse. For more information, check out MrEclipse.com, Eclipsewise, and Timeanddate.com’s pages on eclipses.

October is a good month for sky viewing. For most of the world, the weather isn’t too bad, and clear skies give you a chance to do some exploring. I’ve got a little video up at Astrocast.tv that explains some of the sky sights you can seek out. I talk about the planet Mars, low in the western sky after sunset, along with Saturn, Jupiter in the early morning, and a possible glimpse of Mercury (also in the predawn hour). There’s also the Orionid Meteor shower, and while you’re waiting for it to send some meteors our way, you can search out the Andromeda Galaxy and Perseus Double Cluster (for northern hemisphere explorers) and the Magellanic Clouds and the globular cluster 47 Tucanae in the southern hemisphere skies. Check it all out in Our Night Sky.

Lifting the Veil on the Early Universe

The Creation of a Galactic Metropolis

An artist’s conception of a giant protocluster of galaxies forming in the early universe. The galaxies are busy forming new stars while at the same time interacting with each other. Courtesy: ESO/M. Kornmesser

From time to time astronomers give us a peek at the early universe and each time they do, they lift the veil on earlier and earlier time periods of our cosmic history. In recent years, they’ve shown us early “shreds” of galaxies and hints of the first stars to ever form. Galaxies began forming some 500 million years after the Big Bang occurred. As galaxies formed through collision and cannibalism, they also clumped together in clusters. One of the oldest clusters is called the Spiderweb Galaxy (or MTC1138-262) is at the heart of a galactic protocluster that began assembling more than 10 billion years ago.

Astronomers interested in star formation in infant galaxies during those early epochs of galaxy building took a closer look at this cluster using the APEX Telescope in Chile, part of the European Southern Observatory. This telescope is exquisitely sensitive to millimeter wavelengths of light (part of the infrared spectrum of light).  It opens a window on distant universe, allowing astronomers to look for faint glimmers of energy from the early universe. They used something called the LABOCA (which stands for Large Bolometer Camera) instrument to look at the cluster. This camera is essentially a sensitive thermometer that helps astronomers sense any kind of heat above absolute zero.  That means it can detect the glimmers of star formation from the early universe, even if they’re hidden by clouds of dust and gas.

Essentially, the APEX telescope and instruments revealed that there are many more sources of star formation in the region of the Spiderweb than astronomers suspected. Their ability to peek behind the veil of dust that hid parts of the cluster’s activity showed astronomers something of a surprise. Yes, star formation is happening there, growing in the interacting galaxies. But, it is  not where they expected it to be. It’s clustered in a relatively small region of the cluster, and not in filaments of gas and dust strung between the member galaxies, where such events usually occur as galaxies interact. Galaxy collisions regularly set off bursts of star formation, and you often see bluish starburst knots strung out between member galaxies like strings of fuzzy pearls.

So, why is star birth so constrained to a smallish, non-central area of the cluster? Good question. Finding the star formation is great news, but now astronomers need to figure out why it’s occurring in a region where they didn’t expect it to be. What processes are shaping the starbirth nurseries in this cluster? Do they tell us something about how clusters formed in the early universe?  Good questions, which astronomers hope to answer by focusing the massed ALMA array on the region when they get a chance. It should give them nicely resolved looks at the stellar creches in the Spiderweb Galaxy and its siblings in the cluster.

 

 

 

Exploring Science and the Cosmos

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