All Space Considered, Feb 2015 (The Rest)

Comet 67P (Churyumov-Gerasimenko)

While Philae is asleep on the surface of Comet 67P, Rosetta continues to study it from a distance.  A special edition of the journal Science dedicated to Rosetta's findings was published.  There are far too many for me to go into detail here on all of them.  The ESA's blog post on the findings gives a summary as well as resources for follow-up reading.  The one item I will mention that was discussed at All Space Considered is that the surface of Comet 67P seems to have a much higher level of diversity than previously thought.  Two principal ideas were put forward to account for Comet 67P's dual-lobe shape.  It was hypothesized that either two bodies collided and merged or Comet 67P started as a single object and internal processes driven by close approaches to the sun blew off a middle band.  Rather than just seeing one or two different surface types, as would support either of those theories, it turns out Comet 67P has 19 different regions (outlined in graphic below) that accommodate at least 5 rather diverse types of terrain.  Some new theories will have to be put forth to explain Rosetta's findings.

On a more human note, Comet 67P is often referred to as "Churyumov-Gerasimenko" after its two discoverers.  It turns out both of them, Klim Churyumov and Svetlana Gerasimenko, had birthdays in February.

Milky Way's Puffing Black Hole

Another discovery about our Milky Way was that the black hole at the center of it is emitting plumes of material.  Hubble made many observations using background quasars as a reference.  By seeing how the light from these quasars change on the way through the huge outflows, chemical composition, speed and other characteristics could be deduced.  It's not known exactly what caused these huge plumes to be ejected and only further observations will settle the issue.  However, this is, of course, by far the closest instance of such galactic plumes, so we will be able to gather much better data on this than ones we see from other galactic centers.  One idea of what might have caused this is a frenzy of star formation near the galactic center.  Another idea is that a large number of stars got gobbled up by our galactic black hole around the same time, ejecting a lot more gas and other material than normal.  Below is an image describing how the velocity of the material in the plumes was measured.

The EAGLE Simulation

Universe simulation was again fairly successful.  The EAGLE simulation started with nothing more than some energy, a huge simulated volume and the known laws of physics.  It actually ended up creating galaxies, complete with spirals and ellipticals, as well as clusters and superclusters as seen in the current Universe.  It's not clear to me how this differs from Illustris from back in May.  There was no discussion of the differences and similarities between the two, but at least on the surface, they seem to be doing the same thing.  That's a great thing in science because it provides corroboration.  If one had succeeded and the other failed, the most likely cause would have been human error.  In any case, here's a cool visualization of an "instant" in time during the simulation.

All Space Considered, Feb 2015 (Exoplanets)

Exoplanets

Giant Ring System

So January 2015 was a good month for exoplanet news.  All kinds of cool findings were made.  The lead off here has a very cool video to go with it.

There are lots of other pretty artist depictions of this giant ring system, but I like this video because it shows the actual transit data along the bottom.  The transit method is one of the primary ways we've detected exoplanets in the past 10-20 years and usually the data tell us about the planet itself.  In this case, the transit data packed quite a surprise, one whose best explanation at the moment is a huge ring system.  How huge?  When we think "ring system," almost universally people will think of Saturn, with good reason.  It has by far the largest and most prominent ring system in our sun's domain.  If the data we collected really do show a ring system as hypothesized, here's what the behemoth would look like in our sky if placed where Saturn is.

Yup, that's our moon on the left, getting dwarfed

Could this possibly be such a ring system that seemingly only science fiction would dream up?  For me, the most convincing part is the symmetry, that the star had to pass both into and out of the ring system.  I suppose the tilt of the rings and the orbit of the planet with respect to Earth's line of sight to the star might provide enough degrees of freedom to fit any data; but enough experts are convinced that I'm going to believe it for now.

Doubled the Discovered Goldilocks Planets

While the ring system makes for pretty pictures, what exoplanet hunters are really after is Earth-like planets, ones in the "Goldilocks" zone where liquid water on the surface is likely and roughly the same size as Earth.  Well, we found 8 more, bringing the overall total to 16.  Such planets are of extreme interest for at least two reasons.  The first is that human-like life is most likely to exist on such a planet.  There is always the possibility that non-human-like life exists on other planets, but we're of course most interested in the life that we are most compatible with.  The second reason is exploring the possibility of human life somewhere besides Earth.  Mars occasionally comes up as a candidate, but its thin atmosphere makes it a pretty poor candidate.  It is still nonetheless the best candidate in the solar system.  That means to find a truly great candidate, we must look beyond our solar system.

Super-Earths Superer than Earth at Holding Oceans

Another point of discussion was theoretical work done regarding the development of oceans and a planet's ability to retain one oceans once they had been established.  It is, of course, nice if a planet has liquid water.  However, if it is like Mars, that water disappears quickly and the window of opportunity for life as we know it to form is over.  Harvards Center for Astrophysics has determined that planets 2-4 times the mass of Earth seem to be the best at both forming oceans and retaining them once formed.  The main impact of this research is that if we want to look for liquid water, we should target searches for planets in this mass range most heavily.

It bears remarking that the rate of exoplanet discovery in the past 10 years has been just plain crazy.  Not long ago, we weren't even sure if we could detect exoplanets.  Now, we've found more than all but the most popular people have friends on Facebook.  It's almost certain that we'll find more than the single most popular person has friends on Facebook soon.  "Friends on Facebook" may seem a frivolous measure, but I bring it up because it means that for each person you have had any personal interaction with, there is an exoplanet that has been discovered and confirmed.  Given that all of this has happened within a relatively small region of our own galaxy, which itself is only one of hundreds of billions in the observable Universe, and the sheer scale of the diversity and possibilities become incomprehensible rather quickly.

NGTS

In the vein of accelerated discovery, a new planet-hunting telescope saw first light in January. I'm not sure if this was indeed mentioned at All Space Considered, but I think it's important enough to mention.  To date, the space-based Kepler telescope has been doing the lion's share of the exoplanet discovery.  It has been hobbled of late by failing mechanics, but had long surpassed its original mission length and still continues to amazing work even in its current state.  NGTS is a ground-based telescope that will look at much brighter stars than Kepler and sweep out a larger region of the sky than Kepler.  Like Kepler, much of NGTS's work will be to provide candidates for follow-on observations with more specialized telescopes.  Standard transit observations can deduce size, mass and orbit of an exoplanet.  Follow-on measurements use spectroscopy while the planet is in-transit to determine the chemical composition and depth of the planet's atmosphere.

All Space Considered, Feb 2015 (Venus Express)

Venus Express

On February 6, I once again attended All Space Considered at Griffith Observatory.  The highlight of this particular All Space Considered was a video call-in session with David Grinspoon, a man who holds many titles, but was speaking to us primarily as Interdisciplinary Scientist for the ESA's Venus Express mission.  Grinspoon was very engaging in charismatic while telling us about the principal results of the mission.

Active Volcanism

One of Venus Express's goals was to determine if there is active volcanism on Venus.  It has long been hypothesized that there is based on radar images of the surface taken by NASA's Magellan mission.  While Venus Express did not find a smoking gun and no direct image of an erupting volcano was captured, the evidence gathered in favor of active volcanism fell just short of that.  Two pieces of data point towards current active volcanism.  The first was spectral emissivity data.  This indicated that the lava flows found by Magellan were relatively pristine and therefore young.  Below is an image of this emissivity data overlaid onto Magellan radar data.

The red area essentially shows elevated heat levels, something that should dissipate over time.  By looking at the heat, the age of the lava flow can approximated.  The second piece of evidence of active volcanism on Venus was sulphur dioxide content in the atmosphere.  Rather high levels were detected that dissipated quite quickly, strongly indicating that there was an eruption somewhere that Venus Express wasn't looking.

Lightning

Another goal of Venus Express was detecting lightning.  "Smoking gun" evidence for this is even more challenging than volcanism, as anyone who has tried to photograph lightning on Earth probably knows.  However, large electromagnetic spikes were measured and there really is no explanation other than lightning occurring in the upper reaches of Venus's atmosphere.

Polar Vortices

The conversation with Grinspoon went on to quite a few more topics, but the last that I will discuss here are the polar vortices of Venus.  Saturn's hexagon is fairly well-known at this point; and we can even recreate it in the lab.  It turns out Venus may have a similar phenomenon going on.  However, Venus's southern vortex is far more dynamic.  For starters, its center of rotation is not aligned with the  planet's south pole.  It tends to "orbit" the south pole every 5-10 Earth days.  The existence of the vortex already tells us that there is highly dynamic weather on Venus.  An orbiting vortex kicks up the dynamic factor quite a bit.  Things around the vortex are continuously "kicking" it around.  On top of all that, the shape of the vortex changes at quite a rapid pace.  Below is an animated GIF of the phenomenon.

Venus Express had much more to teach us about Venus.  For anyone who's interested, the ESA's Venus Express site is an excellent informational resource.