Jupiter and the Galilean Moons

I happen to be out in my backyard this weekend during that sliver of time when the sky is dark enough to see Jupiter with the unaided eye, but not so dark that the sky is black yet.  Unlike the moon, which is usually visible during most daylight hours, the planets are difficult to spot against a blue sky except at dawn and dusk.  I managed to snap the following picture that also shows the Galilean moons.

I did cheat just a little.  I took a long exposure, which made the sky bluer in the picture than it looked to the unaided eye.  The long exposure is revealed if you click on the picture to enlarge it.  You'll see the motion blur from the Earth's rotation.  I don't have a tracking mount, so I still get "star trails" when I take long exposures at high magnification.

Backyard Astrophotography -- The Big Dipper

Been pointing my camera skyward at night of late.  There's a lot to it, but I'm sort of starting to get the hang of it.  Here is a series of 3 pictures of the Big Dipper with everything on the camera set the same except exposure time.  I like that you can go from a bunch of dots to what are more or less just the principal stars in the constellation (something you'll see much more clearly if you click on the images to get larger versions).

A 30s exposure

A 20s exposure

A 10s exposure

I should note that these are raw images.  Far clearer images can be obtained with stacking.  From what I understand, that's particularly useful when there is lots of detail in the subject (nebulae, close-ups of planets, etc).

All Space Considered, December 2015 (The Greater Cosmos)

Milky Way's Black Hole's Magnetic Fields Measured

Black holes are usually talked about in terms of their gravity.  This is perfectly natural, of course, given both the fundamental nature of black holes and how we humans happened upon them (theoretical anomaly in General Relativity).  However, there's no reason to ignore their magnetic fields.  Luckily, they aren't being ignored.  The Event Horizon Telescope (EHT) took measurements of our own galaxy's central black hole.  For the first time, the resolution of our measurements was able to look almost right down to the event horizon of the Milky Way's central black hole.  This will provide valuable information regarding how jets form around black holes.

Given all there is surrounding a galaxy's central black hole, optical imaging is impossible.  Instead, the EHT looked at "light" with a 1.3mm wavelength.  While the black hole is particularly bright there, the important feature of the light was the polarization.  That gives the most information regarding the local magnetic fields.  It should also be noted that EHT is making use of very long baseline interferometry (VLBI) to mimic a much larger telescope.  This technique improved resolution to the degree needed to make such detailed observations.  Though black holes are hugely massive, their density makes them smaller than one might think.  This particular study was doing the equivalent of looking at a golf ball on the moon.

Planetary Nebulae

A new way to determine the distance to planetary nebula was announced.  The name "planetary nebula" is a misnomer in that they have nothing to do with planets.  However, the name has stuck for historical reasons.  Planetary nebula are actually the remnants of now-dead stars.  Studying them gives great insight into the stellar life cycle.  One thing that has plagued people studying them, however, is that the distances to them is difficult to measure.  Unlike stars, planetary nebula are diffuse in the sky and, as can be seen in the picture below, their diversity makes it hard to pick any given feature to home-in on as an age signifier.

However, scientists have indeed found a characteristic that will allow them to gauge the distance to planetary nebula.  Though not new, it used much more up-to-date and accurate corroborating data.  In addition to publishing the method, which combines reddening and hydrogen emission lines, a catalog of over 1000 distances using this new method was created.

Highest Mass-to-light Ratio Galaxy Found

A galaxy with a record mass-to-light ratio was discovered.  Well, we've known about Triangulum II for some time, but we just discovered that its mass-to-light was a whopping 3500 or so (for reference, the Universe's mass-to-light is about 100).  Mass-to-light is used as a measure of dark matter. If a lot of mass can be inferred at a location, but we see very few stars, we now assume the difference is predominantly dark matter.  If this result stands, it would be an incredible opportunity to study dark matter, as Triangulum II is quite close on a cosmic scale, just barely beyond the furthest edges of our own galaxy, the Milky Way.

Personally, I'm a touch skeptical of this result.  The study is basing its results on the velocities of six stars.  Others have already put forth the alternative hypothesis that the Milky Way is pulling and tugging on those stars to alter their motion.  Nonetheless, I do hope the result is correct and look forward to the follow-on work.

Cheshire Cat Fossil Galaxy

Well, some good science is coming out of this one, but mostly, it's a pretty picture.

This is the Cheshire Cat group of galaxies.  It was posted by NASA the week of the 100th anniversary of Einstein's publication of his General Theory of Relativity.  That theory predicted gravitational lensing and this picture is a particularly amusing example of that prediction realized.  You can read the NASA post for full details about the what's where in this image.  The main features are the eyes, which are two galaxies on a collision course with each other, and four background galaxies that are gravitationally lensed into arcs forming the facial outlines and smile of the cat.

All Space Considered, December 2015 (Exoplanets and Stars)

Exoplanet Formation Imaged

In the past decade or two, we've been finding exoplanets like crazy.  Despite what you may have heard about Kepler's discoveries, there are almost 2,000 confirmed exoplanets with absolutely no slowdown in the discovery rate in sight.  Though Kepler has been hobbled somewhat, the mission scientists and engineers have kept it fairly productive through very innovative and ingenious methods.  Additionally, NASA has a swanky new exoplanet-hunting satellite scheduled for launch next year, TESS.

The big news this month is that we actually imaged a planet forming.  This is the photo released to the press.

This is the LkCa 15 system.  You can see the star's protoplanetary disk on the left.  On the right, you see the planets up close.  While it may not look like much, what's important here is that a particular emission line from planet b shows that lots of material is falling onto it.  That process causes a lot of heat, creating ions that wouldn't be there otherwise.  Those ions are generating the emission line that is strong enough to indicate actual accretion occurring in this very picture.

Most Earth-like Exoplanet Not Very Habitable

Once an exoplanet is confirmed, various factors are used to create an Earth Similarity Index.  Kepler 438b has so far scored highest ESI at 0.88 (1.00 being identical to Earth in the criteria).  Unfortunately, research has shown that it's just too darn close to its host star.  While its proximity to its host star does put it in the Goldilocks Zone, the host star is a red dwarf.  These stars tend to be more active and Kepler 438 is no exception.  A team measured its activity and found that every few hundred days, Kepler 438 lets off a superflare.  The energy of each of Kepler 438's superflares is stronger than the most powerful ones ever recorded of our sun.  These generally lead to coronal mass ejections, which would more likely than not strip Kepler 438b of its atmosphere.  The study's authors did point out that if Kepler 438b has a strong magnetic field, then perhaps it could be shielded from the worst of the coronal mass ejections; however, they did not comment on how likely such shielding is.  Generally speaking, however, it isn't very likely.  If the planet formed that close, it would likely have tidally locked to the star, not leaving much room for the creation of a dynamo strong enough to repel the host star's stellar wind.

Supermassive Stars Shed Material

Observations of VY Canis Major, one of the largest stars in our Milky Way, have shown it shedding material before going supernova.  What's unique about the findings of the recent observations is that the dust grains being shed are larger than previously thought.  It was always theorized that the radiation pressure from the star itself would push the material it sheds outwards.  However, this pressure is very small and can only push material outward fast enough to escape the eventual supernova if the grains are of sufficient size.  The grains found are about 50 times larger than typical interstellar dust.  The other significance of this finding is that such large grains can actually survive the supernova itself, explaining some of the abundances of material in nebulae that we see.

I like the ESO's sense of humor with the title of their news release: Aging Star's Weight Loss Secret Revealed.  The above picture shows VY Canis Major through the eyes of a coronagraph.  The central circle that blocks the light from the star itself allows much more detail of the surrounding to be seen.

Low Metallicity Stars In Milky Way

The abundance of metal in a star can generally be used to age the star.  The less metal it has (in astronomy anything other than hydrogen and helium is a "metal"), the older it is.  This is because stars are creating new elements, first fusing hydrogen to helium, then helium to heavier elements and on up the periodic table.  As time goes on, these elements get cast out into the Universe, helping seed future generations of stars.  The later the generation a star belongs to, the more metal-rich it will be on average.  The general trend in the Milky Way is that older stars are at the edges and younger stars are closer to the center.  This stands to reason since star formation tends to be more frequent in denser areas.

However, the central bulge of the Milky Way is a difficult thing to observe.  There's so much stuff, it's hard to see what's going on.  With careful analysis of some data from the Gemini North telescope, it's been determined that there are a lot of old, low-metallicity stars close to the center of the Milky Way.  This bucks the observational trend, which means it bucks the current theories of how the Milky Way formed.  Chances are pretty good these low-metallicity stars came from a globular cluster or small galaxy that the Milky Way ate some time in the distant past.  However, much more evidence would need to be gathered to state this conclusion with any certainty.

All Space Considered, December 2015 (Our Solar System)

I've realized that I've gone a bit overboard in my desire to connect everything we're looking for in space to the possibility of life there.  While that is a tantalizing possibility introduced by most space research, there are lots and lots of other reasons to explore space too, not the least of which is sheer curiosity.  I'll try and tone the connection to life down a bit, though there may be reason to bring it up on occasion.

Pluto

Since its closest approach to Pluto in July, New Horizons has taken most of the headlines when it comes to solar system exploration; and does so with good reason.  It has improved our understanding of Pluto literally millions of times over.  Alan Stern, the mission's Principal Investigator, told an All Space Considered audience earlier in the year that our previous best images of Pluto couldn't resolve a continent and New Horizons would be able to resolve features just 10s of meters across.  For various engineering reasons, the images of highest resolution are just arriving now.  Here's one of the many stunners.

Since All Space Considered happened, a color version of the above photo (taken from this press release) has been released.  This really illustrates the contrast in geography on Pluto.  To this non-expert, it seems pretty clear the surface is undergoing major changes on a pretty regular basis.  Apparently, to many trained experts, some of the pictures seemed to indicate icy volcanoes on Pluto.  Some features resembling shield volcanoes on Earth were seen in some of the images.  In the words of Oliver White, a researcher at NASA's Ames Research Center, "Whatever they are, they're definitely weird.  Volcanoes is the least weird hypothesis at the moment."  For more details, see this article at space.com.

Titan (Saturn's largest moon)

This moon of Saturn has become a favorite of mine.  Between its size (10th biggest object in the entire solar system), thick atmosphere, rocky terrain, standing lakes of methane and salty subsurface water oceans, it has a level of complexity and strangeness I personally find matched only by Earth.  Some new images of Titan came back from Cassini and, as usual, we saw something we didn't expect.  Here it is.

Titan seems to have a belly button.  That belly button is actually a cloud formed during the transition of Titan's south pole from fall to winter.  We're watching seasons change ON ANOTHER FRICKING PLANET!  There's a full(er) explanation of the whole phenomenon in NASA's press release.  My favorite tidbit is that the clouds form by subsidence (new vocab word for me).  For reasons beyond my understanding, warm gases sink in Titan's atmosphere.  As the warm gases from the northern hemisphere circulates to the colder, southern hemisphere, the sinking takes them through progressively colder surrounding temperatures.  Different gases will condense out at different altitudes, forming clouds along the way.

Phobos (Mars's largest moon, for now)

Mars's largest moon, Phobos, has some funny geological features.  In the picture below, they can be see as striations emanating from the large crater in the lower right.  After lots of analysis, it's been discovered that Mars is pulling Phobos apart.  Tidal forces from Mars's gravity is causing Phobos to stretch enough to cause the fracturing and cracking that is seen here.  This is a bit of a happy accident, as Phobos is surprisingly light.  Its density is only about 1/3 that of Earth or about 60% that of the moon.  This means it's easier for tidal forces to act on it, especially at the fairly close distance Phobos is to Mars.

Based on all this data, it appears that Phobos will be ripped apart in 20 to 40 million years.  On human scales, that's a pretty long time, but on astronomical scales, that's pretty soon.  Also, in the intervening time, we can keep looking at Phobos.  What's really cool about this is that when Phobos breaks apart, it may form a ring around Mars.  It's suspected some of the inner planets may have had rings in the past, when the structures and material in the solar system were much more dynamic.  It would be cool if one of the inner planets could join the gas giants in having a ring.

Nuclear Fusion? Maybe, maybe ...

We're trying to make stars on Earth.  Luckily for everyone's weight, there isn't enough mass on Earth to make a star the usual way, via gravity.  Instead, we're trying to initiate fusion in a controlled manner, the true holy grail of clean energy for many decades.  Fuel for fusion is abundant and safe and the waste byproducts require far less special care than their fission counterparts.  The standard joke about fusion is that it's always 50 years away.  While true in some sense, people who actually work on fusion would tell you that it's been $80 billion away for decades.  I always like to show this graphic made by Geoff Olynyk when "fusion will always be decades away" rears its ugly head.

Way back in 1976, these were the projections for when we might have fusion given various levels of funding.  Even then, they had the humor to label the projected 1978 level of funding "fusion never."  While I tend to take graphs like this with a grain of salt (predicting the future is hard), the absolutely dreadful level of actual funding is far more astonishing to me.  Do you know how little money $80 billion spread over 15-30 years is compared to a decades-long Cold War?

Hyperbole aside, I let fusion lapse from my attention a bit.  From the "NUCLEAR BAD!!!" camp to the "That's science fiction" to the blank stares, it just didn't seem like the collective fortitude required to attain fusion was there.  I also saw that ITER, the main tokamak project in the world right now, was having difficulties, technical, economic and political.

Then, along came Weldenstein 7-X (W 7-X).  Not being a nuclear engineer nor having quite the time to delve fully into all the tokamak alternatives, I didn't even know what a stellerator was a few months ago.  Glossing over many details, I think Thomas Klinger, the Scientific Director of W 7-X, put it best.  "They are both terrible beasts.  Our's [stellerator] is a beast to build; your's [tokamak] is a beast to operate."

A tokamak is basically a giant magnetic donut.  Intense magnetic fields confine a plasma hot enough to initiate nuclear fusion.  The big problem: the plasma wants to radiate outwards from the center, forcing tokamak designers to jump through all kinds of hoops to keep it on its circular path.  A stellerator, on the other hand, is ... is ... well ... hard to describe.  Here's a picture.

You can go to ScienceMag, where I got this picture from, for further details.  The idea is to fight the outward radiation that tokamaks contend with by making the plasma twist around as it "orbits."  In my completely non-expert understanding, just when the plasma wants to go off course, you twist the course so it comes back in, which results in the weird, twisty thing pictured above.  W 7-X just turned on for the first time Thursday (Dec 10).  It did everything it was supposed to do and the project participants are pleased as punch.  Even if W 7-X performs exactly as designed for the remainder of the project's duration, it still won't generate commercial levels of energy.  However, it is an important research platform and demonstration of fusion's potential as a clean energy source.

I really hope some form of fusion finally makes its way to commercial usage eventually.  We have enough fuel on Earth to produce energy at current levels for millions of years and that fuel (heavy water and lithium) is in places we don't have to fight wars to secure.   If this really works and does so soon enough, perhaps the inaction at the Paris climate talks won't matter.

All Space Considered, November 2015

Earth

It may seem a bit odd to start a post about space with Earth. While we do for the most part study space because we're just plain interested, it is nice for knowledge gained by studying things beyond Earth to help us understand our home planet and vice versa. Here is a perfect example.

Some rocks found in Australia were found to have Carbon-12, a chemical consistent with known life processes. What makes these rocks interesting is that they are 4.4 billion years old. The Carbon-12 is dated to 4.1 billion years ago. Here is the primary image being shared of the discovery.

Why is this a big deal? Earth is only thought to be about 4.6 billion years old. Prior estimates of the oldest known life forms is 3.8 billion years. This discovery, if it holds up under scrutiny, effectively reduces the amount of time required for life to form by about 40%. Further, it shows that life can form under much more hostile conditions than previously thought. Around 4.1 billion years ago, Earth itself was much warmer, was getting hit by asteroids and comets a lot as well as experiencing much higher levels of volcanism than at the current time.

How does this affect our understanding of life beyond Earth? Well, life beyond Earth seems to only get more likely as our knowledge increases. The abundance of planets that can harbor liquid water, the abundance of water itself in space and the number of Earthbound extremophiles (organisms that thrive in conditions seemingly hostile to life) are all recent developments that increase the likelihood of life elsewhere. The fact that life could form so early on Earth ratchets up the likelihood of life elsewhere in the Universe just a little bit more.

Mars

Regarding the idea of life elsewhere in the Universe, Mars was once a darling. In some sense, it still is. However, the prospect for "life on Mars" has slowly been amended to "life on Mars in the past." What we see today on Mars is just not very encouraging in terms of finding life now. However, with regard to life on Mars in the past, things keep looking better.

Deep Lakes

Mars appears to have had very deep lakes in the past. By analyzing sedimentary data collected by theCuriosityrover, it looks like a lake may have been as deep as 800m (half a mile). For perspective, that's twice as deep as the deepest point in the Great Lakes. Here is one of the images studied.

Such large standing bodies of water would be very helpful for the development of life as we know it. Mind you, sedimentary data can only be collected in Curiosity's immediate vicinity. Who knows what else might be found if we could only look elsewhere?

Atmosphere Stripping

Another Mars result was the confirmation that the solar wind is stripping Mars' atmosphere. The usual story told about Earth is that our magnetic field keeps the solar wind from being too strong when it hits our atmosphere. As a result, Earth loses very little of its atmosphere. Mars stands in stark contrast. With no global magnetic field, the solar wind plows into Mars' atmosphere, flinging portions of it beyond the planet's gravitational reach. This story of atmospheric erosion was confirmed numerically byMAVEN'sdata, which was used to produce the following video.

If we run the process of the solar wind stripping Mars' atmosphere back billions of years, a rather significant atmosphere would have been possible. Between this and the deep lakes, an ancient Mars and current Earth would be more similar to each other than the current-day Mars.

Jupiter

TheHubble Space Telescopestared directly at Jupiter for a solid 10 hours. The average day on Jupiter is about 10 hours, which means almost every point on the planet was imaged twice. This is part of theOPALprogram, which will fully image every outer planet annually. Often, it is not the single still image that provides useful information, but the accumulation of data over time. It isn't clear exactly what will be learned through future imaging of the other outer planets, but the pictures sure are pretty.

Already, the rate of the Great Red Spot's shrinking has been measured and a band of wave-like structures was observed. These waves had only been observed once before. Until now, it had been presumed a fluke, which is now clearly not the case.

Enceladus (Saturn)

The Cassini spacecrafttook its deepest dive through Enceladus's plume. Early on in Cassini's tour around Saturn, images showing huge geysers spewing material out of Enceladus flung it to fame. Follow-up missions determined that there is a sub-surface ocean sourcing the plumes. It was also discovered that these geysers help to source the E-ring with material. Only a few images have been released so far of this latest deep dive. Because of the size of the full data and the bandwidth available, full sets of high resolution images won't be available until 2016. However, the detail of the surface in the pictures already released is pretty amazing. Each pixel represents 50 feet across, the size of a fairly modest home.

The principal purpose of this dive, however, is not close-up imaging of Enceladus' surface, though that is a nice benefit. Scientists are most interested in the chemical composition and make-up of the plume. They are also interested in the physical nature of the plume. Though it has been imaged, the depth, density and rate of material discharge is not well-known or understood. All of this information will paint a better picture of what mechanisms are actually producing the plumes and how long they have been going on. As usual when water is involved, the conclusions will also have strong implications regarding life on the moon.

Overlapping Stars (aka VFTS 352)

Two stars were found to be so close that they are actually sharing material. Collectively, the binary is known as VFTS 352. Binary star systems that share material are known as "contact binaries" or "overcontact binaries." VFTS 352 is by no means the first contact binary system discovered. However, it is the most massive, collectively about 57 times the mass of our sun. I'm not sure why theESOdidn't release an image used by the scientists; but this artist's rendition is kinda pretty.

VFTS 352 is also unusual in how close in size the two components of the binary are. As a result, material isn't being sucked from one to the other, as is most common. Instead, the two stars are actually sharing material in what might be thought of as a stable configuration. What is potentially unique about this system is that the stars may both go supernova. If that happens, a binary black hole may form, something that hasn't been accounted for by current models of stellar evolution. Personally, I'm a little skeptical that such a thing will occur; but, I'm far less qualified to speculate about such things than the experts at ESO.

Comets

Comets are mainly from the Kuiper Belt and Oort Cloud. The material in these regions is considered primordial in the sense that they have changed very little since our sun began fusing. As such, they are a proxy for the conditions in the very early formation of our solar system. Discoveries related to comets, particularly their composition and chemistry, not only helps us determine which theories of solar system formation are more likely, but how quickly the complex reactions required for life might have formed. This month, two comets shed some light on these issues.

Drunk Comet (Lovejoy, of course)

Comet Lovejoy was found to have large amounts of alcohol in its tail. There are lots of forms of alcohol, but we are in fact talking about the kind that gets Samuel L Jackson drunk. Alcohol is a relatively complex molecule in the context of a pre-planetary solar system. If the extreme heating and cooling from the sun arising from comets' highly eccentric orbits brings about such complex chemistry, then life on Earth would not necessarily have had to start from complete scratch. The process that led to life on Earth could have been jump-started with complex chemicals brought by comets rather than having to synthesize everything from simple molecules like water, carbon monoxide and nitrogen.

Oxygen From Comet 67P (Churyumov-Gerasimenko)

The oxygen atom is very abundant in the Universe. However, molecular oxygen (O₂) is quite rare in space because it is so reactive. O₂can easily combine with hydrogen to make water, for example, and can even combine with free oxygen atoms to create ozone (O₃). Nonetheless, the Rosetta spacecraftdetected O₂in the tail of Comet 67P. Finding O₂in a comet doesn't fit with our current models of solar system formation. The mechanisms required to trap O₂within a comet are simply not there. Such a mechanism will now have to be added to account for theobservations made by Rosetta.