Monthly Archives: September 2008

Astronomy outreach, astronomy research, space weather

Space Weather FX

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Episode 2

The second in our series of videos (vodcasts) on space weather has gone live on the MIT Haystack Observatory Web site. We are currently working on a third episode to be out in early October. The series teaches about space weather and its effects on our planet and our technology.

This second episode is just about 4 minutes long and talks about the main ingredients of space weather:  magnetic fields and plasmas.  It was a challenging one to produce because I wanted to find a suitable-level model of magnetic field generation inside our own planet, and finally ended up creating my own. I also ended up creating a basic little visual sequence about how plasmas form.

Episode 1 is an introduction and is 6.5 minutes long. Both star scientist Philip J. Erickson (who is an atmospheric researcher at MIT Haystack) and yours truly gets to do the voice-over work. The episodes are aimed at about a 5th or 6th grade level and are ideal for classroom or home use. They’re accompanied by a page of links for further investigation, and we’re working on getting closed-captioning versions ready, as well. Eventually we’ll get an evaluation form up there, so if you’re a teacher and you’re using these, we’ll be interested in your feedback. Check ’em out!

astronomy

Clusters Moving along in a Dark Flow

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Scientists Detect Subtle Cosmic Motion

Hot gas in moving galaxy clusters (white spots) shifts the temperature of cosmic microwaves. Hundreds of distant galaxies seem to be moving toward on patch of sky (colored purple). NASA/WMAP/IA Kashlinsky, et al.
Hot gas in moving galaxy clusters (white spots) shifts the temperature of cosmic microwaves. Hundreds of distant galaxies seem to be moving toward on patch of sky (colored purple). NASA/WMAP/IA Kashlinsky, et al.

Oh hey, now this is neat. Complex, but neat. A team led by astronomer Alexander Kashlinsky at NASA’s Goddard Space Flight Center, is looking out at distant clusters of galaxies have been tracking the motions of those clusters as they move through space. And, they’ve found something unexpected, something they are calling “dark flow.”  Essentially, the motions of those clusters have a little “outward tug” that seems to imply a gravitational attraction by something (matter) that lies beyond the cosmic horizon. This tug is independent of the clusters’ own motions and it can’t be accounted for by the expansion of space.

How did astronomers find this dark flow?  They used the Wilkinson Microwave Anisotropy Probe (WMAP) to measure the photons of microwave light as they pass by and are scattered by hot x-ray-emitting gases in the clusters. Essentially, the astronomers dug into the spectra of the scattered light to look for a very tiny shift in the microwave background’s temperature in the direction of the clusters. They looked at a large number of clusters using the technique and found this motion that seems to affect clusters up to 6 billion light-years away. When they measured the motion, they clocked it at nearly 3.2 million kilometers per hour and its direction of flow points directly at a 20-degree-wide patch of sky between the constellations Centaurus and Vela.

What does this mean? You can read more about the finding in a Goddard press release. Essentially, however, astronomers are still refining the measurements, but it seems safe to say that it means stuff is moving faster at greater distances than they expected. And, it’s directional, which is challenging to explain unless you invoke some kind of gravitational influence of unseen matter in the attracting region.  What’s there?  Good question.  Stay tuned!