No Mistaking Astronomical Objects

On Starts With a Bang, Ethan Siegel makes headway on his tour of “110 spectacular deep-sky objects” first cataloged by Charles Messier in 1758.  Before powerful telescopes were developed, the heavens consisted of the sun, moon, stars, a few bright planets, and the rare passing comet.  Comets were actively sought by men like Messier, who one night saw a bright smudge—too ill-defined to be a star—that “neither brightened nor changed position nor altered in appearance over the subsequent nights.”  He had spotted the beautiful Crab Nebula, an expanding lacework of stardust blown out by a supernova within our own galaxy.  Unknown to Messier, some of his nebulae were entirely different galaxies, millions of light years distant, a structure scarcely conceived of in the 18th century (and not proven, on the basis of redshift, until 1912).  Other Messier objects turn out to be spectacular star clusters, such as M13, which contains about 300,000 stars “from Sun-like ones down to red dwarfs and white dwarfs, a few blue stragglers (common to globulars), and a few red giant stars” within a diameter of 145 light years.  But all these wonders of the universe looked about the same to Messier: things not to confuse with comets, ice orbiting the sun.


No Star Unturned

On Dynamics of Cats, Steinn Sigurðsson sifts through Hubble’s vast catalog of stars, gas, and galaxies, looking for a diamond in the rough. Many images captured by the Hubble Space Telescope have never really been looked at; Sigurðsson says “In some cases the PI died before doing so. More usually these are engineering test images, or ‘parallel images,’ where a second camera was set to take images of wherever it happened to be pointed.” The European Space Agency wants your help to search through these pictures. In 2004, Hubble resolved the famous Ultra Deep-Field with 10,000 galaxies across three black arc-minutes of space. On Starts With a Bang, Ethan Siegel leads us through a new image of 200,000 galaxies produced by a telescope called VISTA. VISTA combined over 6000 exposures of a section of sky “about eight times the area of the full moon,” or about 800 times the area of Hubble’s UDF. Siegel says “the only remarkable thing about this patch of space is how unremarkable it was!” And there’s a lot more where that came from.

Bringing Knowledge into Focus

The Universe is a little less than 14 billion years old. Humanity, maybe 200,000. We have reached for knowledge at every step, and recorded what we could. The pace of our knowledge seems to accelerate; the 20th century tranformed our understanding of reality, as had the previous millenium. In 2011, we gather more information than ever before, and our knowledge seems almost complete. But it’s funny how things change. On Built on Facts, Matt Springer says James Clerk Maxwell’s electromagnetic equations are as good today as they were in the 1860’s, despite a little thing called relativity. Matt writes, “Lorentz covariance is built right in, though it’s a bit hidden. But Maxwell and Faraday and Ampere and the rest didn’t know that.” On Starts With a Bang, Ethan Siegel shows how improving telescopes turned an 18th century “smudge” into a 19th century “nebula.” It took until 1929 for a man named Hubble to discover that M31 is a separate galaxy: Andromeda, our nearest neighbor. Twenty years ago, NASA launched a telescope into orbit and named it after Hubble. They pointed it at the darkest part of the sky for days, and discovered little galaxies everywhere. But Hubble’s heyday is over, and its successor is on the chopping block.

What Makes a Planet?

Greg Laden draws our attention to an object named Vesta, which by itself makes up 9% of the asteroid belt. Greg says “if you take the largest handful of objects in the asteroid belt, Ceres, Vesta, Pallas and 10 Hygiea, you’ve got half of the mass of the entire thing, according to the most current estimates.” According to NASA, Vesta is even differentiated, meaning it was once hot enough to form a core, mantle, and crust. On Life at the SETI Institute, the Analysis Lead on NASA’s Kepler project explains how to spot a planet from hundreds of millions of miles away. Dr. Jon Jenkins says “We’re looking for one part per 10,000 drop in brightness caused by this tiny planet blocking a small fraction of the light from the star.” Kepler finds about ten new planetary candidates every day, and can also “hear” starquakes, the “songs of the stars.” Finally, on Starts With a Bang!, Ethan Siegel brings planetary dynamics closer to home. He says earthquakes occur as the planet differentiates itself, bringing the heaviest elements to the core, and the lightest elements to the surface. Every time this happens, the world spins a little faster.

We are All Scientists

On Uncertain Principles, Chad Orzel differs with Neil Degrasse Tyson, saying that scientific thinking isn’t that new, or that exclusive, and in fact has defined humanity from the very beginning. Chad describes science as “a method for figuring things out: you look at some situation, come up with a possible explanation, and try it to see if it works.” We start with idle hands, move on to stone tools, furrowed fields, Egyptian pyramids, Roman aqueducts, and now the pinnacle of our drive to master the universe, the iPad 2. In a follow-up article, Chad dismisses stereotypes of the scientific elite, saying “scientific thinking and scientific problem solving use exactly the same mental skills that you apply to pretty much any task more complicated than breathing.” Charlie Sheen provides a good example on Dean’s Corner, where he was recently described by Neil DeGrasse Tyson as being “more scientifically literate than most.” Dean Toney has his doubts about Tyson’s assessment, but Sheen does ask a pretty pointed cosmological question.

Still in the Dark

The universe remains a mysterious place, and one of the biggest mysteries confronting astronomers today is that “the amount of mass we can see through our telescopes is not enough to keep galaxies from spinning apart.” Since the 1930’s, this shortfall has been covered by dark matter, a hypothetical substance which has never actually been observed. On the Weizmann Wave, we can consider an alternative called MOND (Modified Newtonian Dynamics) which “posits that gravity works differently on the intergalactic scale.” In fact, University of Maryland researcher Stacy McGaugh recently published a paper that says for low surface brightness galaxies, MOND works better than dark matter. But on Starts With a Bang!, Ethan Siegel says MOND was designed to work for rotating galaxies, and “the problem is it doesn’t do anything else.” To successfully model large-scale phenomena such as the cosmic microwave background radiation, there needs to be five times more mass in the universe than we can observe. But what or where it is, nobody knows.

Astro News Near and Far

On Life at the SETI Institute, Dr. Franck Marchis shares the latest results from Kepler, a telescope in an Earth-trailing heliocentric orbit which keeps a distant eye on 156,453 stars. Kepler watches for tell-tale reductions in brightness, which “could be due to the transit of an exoplanet passing between its star and us.” As of Tuesday, Kepler has identified 1202 likely new exoplanets, tripling the number of known worlds beyond our solar system. These results suggest that out of the 200 billion stars in our galaxy, “several hundred million of them could have an exoplanet with a surface temperature adequate to sustain liquid water.” Great, now where’s our hyperdrive? Ethan Siegel also reports that Hubble has detected a galaxy at a record-breaking redshift of 10.3, making it the most distant galaxy ever observed. If it still exists, it’s probably full of planets too.