So Much Astronomy

And So Little Time

It’s not that there’s nothing to blog about it the world of astronomy these days. It’s that there’s too much good stuff!

Saturn

Saturn's HexagonCassini takes amazing picts of Saturn’s northern hemisphere, and sees cyclones.

The new-found cyclone at Saturn’s north pole is only visible in the near-infrared wavelengths because the north pole is in winter, thus in darkness to visible-light cameras. At these wavelengths, about seven times greater than light seen by the human eye, the clouds deep inside Saturn’s atmosphere are seen in silhouette against the background glow of Saturn’s internal heat.

– And the hexagon is still there!

Winds reach over 150 meters per second (325 miles per hour) at 88.3 degrees south latitude, just outside the first bright ring nearest the pole. The pole itself is covered by a small cloud some 600 kilometers (about 375 miles) wide. The cyclone reaches out some 12,000 kilometers (7,500 miles) from the pole, bordered by the hexagon. This hexagon is populated by fast-moving clouds which also reach speeds of over 500 kilometers per hour (300 miles per hour).

Mosaic of Enceladus, South
It sort of reminds me of the last time I made (real – not instant) oat meal in a pot. When it starts to bubble, a kind of oat-meal foam develops, and always seems to make a hexagon – not a ring – of stuff circling the center of the pot. Interesting.

If that wasn’t enough for Cassini to do, it also buzzed by Saturn’s moon Enceladus at a mere 25 km distance. That’s 16 miles – a mighty close shave.

We’re Being Watched!

Did you know that the Earth is being watched from space? Of course you did.

Deep Impact is on a long cruise toward a second cometary encounter, with Hartley 2 in 2010; but in the meantime, astronomers are using Deep Impact’s defocused high-resolution imager to study known transiting exoplanets, and also to study Earth as though it were an exoplanet. What’s a transiting exoplanet? It’s a planet that orbits another star, which has been detected from Earth by the way it dims the light from its star as it crosses in front of the star on its orbit. In order for a planet to be detected this way, we have to be looking at the star system edge-on, so it’s only possible for us to detect such exoplanets around the small fraction of stars whose planetary disks just happen to be oriented that way.

David Grinspoon presented the results of a similar experiment being performed by Venus Express. At Venus Express’ distance from Earth, its highest-resolution VIRTIS instrument can’t even resolve Earth — it’s always much smaller than one pixel — which is actually a better analogue to future studies of extrasolar planets. If VIRTIS can’t see Earth as a disk, it does get excellent data on Earth’s spectrum, which is fun to study from a distance because of all of the different sources of variability: the spectrum changes as Earth rotates, bringing more continents or more oceans into view; it changes as weather patterns increase or decrease cloud cover and change their distribution; it changes with the seasons, as more or less ice covers the northern hemisphere (the southern hemisphere, having much less continent, shows much less seasonal ice cover variability); and so on.

More news and images here.

The Mars Science Laboratory, the MSL, Is Not Dead, Yet

The Mars Science Laboratory, the next generation of Mars rovers slated to head to Mars in 2009, is still alive, for the time being. The car-sized rover designed to look for life on Mars is over budget and behind schedule due to technical problems, and NASA officials met today to discuss their options. Potentially, Congress could pull the plug on the mission if cost overruns go too high. NASA Administrator Mike Griffin and Science Associate Administrator Ed Weiler were briefed, and met with mission managers in attempt to work out a potential solution. In a press briefing today, Doug McCuistion, director of the Mars Exploration Program at NASA headquarters said the rover’s progress will be assessed again in January, but the mission will need more money.

More on that, here and here.

Hubble

And speaking of not-dead-yet, I noted last week that the Hubble Space Telescope had experienced a significant failure. Side A of it’s Science Data Formatter (SDF) stopped working, and could not be revived. The news this week is that the review committee found no reason to not turn on SDF side B and resume science.

Additional testing demonstrates Side A no longer supports the transfer of science data to the ground. A transition to the redundant Side B should restore full functionality to the science instruments and operations.

The transition to Side B operations is complex. It requires that five other modules used in managing data also be switched to their B-side systems. The B-sides of these modules last were activated during ground tests in the late 1980’s and/or early 1990, prior to launch.

The Hubble operations team has begun work on the Side B transition and believes it will be ready to reconfigure Hubble later this week. The transition will happen after the team completes a readiness review.

Hubble could return to science operations in the immediate future if the reconfiguration is successful. Even so, the agency is investigating the possibility of flying a back-up replacement system, which could be installed during the servicing mission.

This really, really impacted (and impacts) the Hubble Repair Mission, which had been slated to launch today, 14-Oct. NASA is going to re-jigger that mission.

The Sun is Still Quiet!

Amazing picts. Check out the amazing animation – image #9 at the linked site.

The Universe Is Lop-Sided.

One of the basic tenants of cosmology is that the universe is basically uniform. No matter which way you look, you’ll see pretty much the same thing. It’s an assumption, but without it, it gets really, really hard to do science and make sense of some of the observations. So last month came the news of a strange sort of “flow of dark matter”, moving like a river, whose presence was made known only by its effects on a distant cluster of galaxies. Now it seems that two Canadian researchers have found that the local part of the cosmos is not even expanding uniformly. It’s rushing outward at ever expanding rates that are different in one part of the sky than in the other.

A group of researchers have discovered that our particular part of the Universe – out to a distance of 400 million light years – is not expanding uniformly in all directions as expected. To be exact, the expansion is faster in one half of the sky than in the other. “It’s as if, in addition to the expansion, our ‘neighbourhood’ in the Universe has an extra kick in a certain direction,” says Mike Hudson from the University of Waterloo in Ontario, Canada. “We expected the expansion to become more uniform on increasingly larger scales, but that’s not what we found.” If confirmed, their findings will result in a new understanding of the origin of structure in the universe and possible revisions to the standard cosmological model.

It’s not just happening in distant galaxies at the edge of the visible universe, either – it’s happening right here.

In particular, these researchers were attempting to address a longstanding question about the origin of the approximately 600 km/s peculiar velocity of the Local Group of galaxies, with respect to the Cosmic Microwave Background.

Using several different surveys they discovered that about 50% of the Local Group’s motion is faster than anticipated.

The local group includes the Milky Way and Andromeda galaxies, and about three dozen lesser “dwarf” galaxies. Gee – it’s almost as if we’re living in a bubble!

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