On August 17th, 2017 we learned about

Eclipse experiments designed to exploit the Moon’s shadow as it slides across the Earth

Monday’s solar eclipse will be exciting, strange, and possibly cause all kinds of tumult and chaos, which is pretty impressive considering it’s technically just a big shadow sweeping across the Earth. For all of the hype and hoopla, the upcoming total eclipse does offer some unusual opportunities for actual scientific research. Researchers have many experiments planned for the Moon’s shadow, many of which don’t even relate to the Moon itself. Instead, they’re looking at the Earth, Mars, Mercury and the composition of the Sun.

Earth’s atmosphere

One of the larger-scale studies planned for the eclipse will look at how a lack of sunlight changes the Earth’s ionosphere. This layer of atmosphere is normally bombarded with ions from the Sun, protecting those of us on the surface of the planet while also setting off the colorful auroras we call the Northern and Southern Lights. During the eclipse, the Moon will be intercepting those ions, and so volunteers will be measuring how this brief drop in activity affects radio wave transmissions through an unusually calm ionosphere.

Mimicking Mars

Another experiment planned for Monday involves releasing 50 high-altitude balloons into the Moon’s shadow so that we can see how a few moments in the stratosphere affects bacteria. Alongside each balloon is a metal plate swabbed with Paenibacillus xerothermodurans bacteria, which are noted for their incredible durability in harsh environments. Since it’s hard to ensure spacecraft are completely sterile before they arrive at another planet, researchers want to see how these bacteria might hold up in tough environments. The stratosphere’s thinner air, low temperatures and higher radiation levels are already a good proxy for other worlds, but during the eclipse these attributes will all be shifted to a point that closely resembles the surface of Mars. So once the balloons are recovered, researchers will get a chance to see how P. xerothermodurans might hold up on the Red Planet.

Measuring Mercury

Looking a bit deeper into space, there are plans to take advantage of the blocked sunlight to get a better look at the planet Mercury. Mercury’s proximity to the Sun makes it hard to measure, as the light and radiation levels are somewhat overwhelming for most instruments. So when the Moon makes things a bit darker, scientists plan to measure the changes in temperature around Mercury from special airplanes fitted with sensors. These planes will fly in the path of totality, or where the Moon completely blocks the Sun, in order to have more than the two minutes and 40 seconds anyone on the ground could hope for. They’ll also be flying at high altitudes to help bypass distortion that might be introduced by the Earth’s atmosphere.

Studying the Sun

Finally, at least one study will be looking at the Sun itself, which seems appropriate considering the nature of this event. Actually, scientists will be gathering data on the Sun’s corona— the wispy outer layers of plasma that will be visible during totality. As with the study of Mercury, instruments mounted on special aircraft flying at over 470 miles per hour will collect data for around six minutes to try to figure out how the Sun’s outer layers are composed, and why they’re hotter than the inner layers of the Sun. Previous measurements have found that the outer layers of the sun are hotter than most models would expect, and researchers how that this new data will help explain how that’s possible.

And of course, if anything is inclusive, we can all try again during the next total eclipse, which is only three years away if you can make the trip to Chile.

 

 

Source: Solar Eclipse-Chasing Jets Aim to Solve Mystery of Sun's Corona by Tom Metcalfe, Live Science

On August 15th, 2017 we learned about

Even the dimmed sunlight from the solar eclipse can pose a danger to your eyes

Odds are that you’ve never directly viewed a solar eclipse, and you probably shouldn’t start any time soon for the sake of your eyeballs. While the eclipse does have interesting effects on our atmosphere, there’s nothing about the Moon blocking the Sun that magically transforms good sunlight into something dangerous. The sunlight is actually always dangerous, but most of the time it’s bright enough to remind us not to try and gawk at it. Even what seems like a small amount of light can be a health hazard to your eyes, so it’s very important to protect your peepers from the sun when things go dark on August 21st.

Our bodies are bathed in sunlight whenever we’re outside, and it’s obviously not such an immediate problem. Most skin can withstand short exposure to ultraviolet light (UV) without too much wear and tear, and our eyes handle the indirect UV light pretty well (although wearing sunglasses is certainly a good idea.) The reason this all compounds when viewing an eclipse is the that you’re looking right at the sun, and that light can be focused through the lens of your eye. Like a magnifying glass focusing sunlight to start a fire, your lenses focus light on the back of your at the retina. The intensity of directly-focused sunlight can quickly damage your cells by creating reactive molecules called free radicals, which then go on to kill the cell.

Safer ways to stare at the Sun

In most cases of this kind of damage, the damage is somewhat limited. The retina will basically be left with gaps where cells have been killed, and you will have a new set of blind spots in your eye to contend with. Sometimes people recover from this damage, but sometimes they’re left legally blind, as they can only see with the peripheral vision that wasn’t torched by the sun.

This isn’t to say that the only way to enjoy an eclipse is to avoid it. While your sunglasses are in no way up to the task of protecting your eyes when viewing an eclipse, solar-viewing glasses are designed to only allow a safe amount of light, meaning around 0.00032 percent of normal sun exposure. Alternatively, you can view the eclipse in the same way you usually take in sunlight— indirectly. A simple pinhole camera will let you safely watch a projected image of the Sun as it gets blocked out, all without staring right into the sky. If you’re looking for a closer look, don’t use your favorite telescope or binoculars unless you have specific filters for that as well, since that’s basically focusing sunlight at your retina even more effectively than your own eye’s lens can do.


My third grader asked: Isn’t the sunlight blocked enough to be less of a problem?

It takes very little sunlight to harm your eyes, especially when it’s being focused into your eyeball. However, once the Moon completely blocks the Sun during totality, it’s recommended that you take off your protective eyewear, as things will otherwise be too dark to see. With luck, you’ll get a peak at the Sun’s atmosphere around the outer rim of the Moon, and this light won’t be coming directly at you to cause harm. As soon as the Moon starts to move out of the way though, get your glasses back on since any direct sunlight can be a problem.

Source: If the Sun Is 93 Million Miles Away, Why Can't We Look Directly at It? by Rachael Rettner, Live Science

On July 24th, 2017 we learned about

Meteorites may have delivered the metals we find on Earth and Mars

Even if you’ve visited a mine, you still might not appreciate where metals come from. Humans have been digging metals out of the ground for thousands of years, but we’ve only been digging that metal out of the planet’s crust. This is weird, because when the Earth was forming billions of years ago, most of the precious metals like gold and platinum sank to the planet’s core with the iron that now dominates that space. That should have made those metals inaccessible to anyone on the surface, and yet we happily make use of these metals on a daily basis. It’s quite possible that the metal we find in the Earth’s crust actually came from space.

Assuming that our “native” gold, platinum, copper and more are all buried in the center of the planet, the shiny stuff we do dig up would have started on a meteorite. Billions of years ago, its hypothesized that a barrage of meteorites covered the Earth with a fresh supply of metals. Some of those metals were simply buried in the planet’s crust, while others may have been absorbed as deep as the mantle where they could have been churned and moved to new locations. Over time, some of these metals could have been pushed closer to the surface thanks to seismic activity, leaving us with situations like ancient Cyprus, where copper was found in such abundance we named the metal after the island.

Massive impacts on Mars

A twist on this model has also been proposed for other planets. Mars currently lacks the tectonic activity that could have moved and brought metals to its surface, and yet the Red Planet’s southern hemisphere seems to have plenty of metals that shouldn’t be there. That region also has a lot of scars from ancient impact craters, which helps support the idea that the metals on the surface of Mars were also delivered via meteorite billions of years ago.

In the proposed model, a huge meteor hit the planet, not only loading it with a new supply of metals, but also kicking up debris that would eventually coalesce into at least one of Mars’ two moons. It’s a tidy hypothesis, and it fits well with everything from concepts surrounding how planets are formed to why the surface of Mars’ northern hemisphere appears to be a different age than the southern hemisphere.

Source: Where does all Earth's gold come from? Precious metals the result of meteorite bombardment, rock analysis finds, Science Daily

On July 16th, 2017 we learned about

High-speed ions make Comet 67P a surprising source of molecular oxygen

There’s a lot of oxygen in space, but not in a form you can breath. Thanks to the respiration of plants on Earth, our bodies have evolved to use O2, known as molecular oxygen, to pull off our own metabolic processes. Outside of our delightful atmosphere, the most likely place to find oxygen in the cosmos is bonded to other elements like hydrogen and carbon. O2 isn’t distributed equally around the universe, and scientists were starting to look at it as a marker of an Earth-like, habitual planet. However, newly released data from the Comet 67P/Churyumov-Gerasimenko is making us reconsider this most precious molecule yet again.

When the Rosetta spacecraft first reported molecular oxygen near Comet 67P, the assumption was that it was being released from deep within the comet’s core. As the comet got closer to the Sun, it warmed up, melting ice and loosening up, releasing gases that were normally frozen solid, including O2. This O2 would have then been some of our solar system’s original supply of oxygen, created 4.6 billion years ago alongside our Sun. However, unrelated research serendipitously suggested that O2 might not created as infrequently as previously assumed.

Synthesizing O2 with solar wind

Konstantinos Giapis looked at the data from the Rosetta spacecraft not from a geologists perspective, but from his experience as a chemical engineer developing microprocessors. His work involved studying the interactions between high-powered ions and semiconductor surfaces, usually for the purpose of improving memory components in computers. Giapis happened to be curious about this data from space, and recognized that the oxygen on Comet 67P was emerging in similar conditions to those he usually created in his lab.

The emerging hypothesis is that the molecular oxygen seen wafting off of Comet 67P isn’t from the birth of the solar system, and is instead being created as the comet orbits the Sun. Water molecules from ice inside the comet are indeed being released, but ions from the Sun, collectively known as solar wind, are actually breaking those water molecules apart. More oxygen is also being freed from rust and sand on the outside of the comet, and these loose atoms can then bond into new O2.

If this is confirmed, it’s good to know but certainly complicates our model of the universe. There had been hope that O2 could be an indicator of life on distant exoplanets, but knowing that it these molecules can be made with debris and the ions means that it’s not always going to be a sign of respiration. O2 is still rather unusual, but we now know there are more ways to get a hold of some if you don’t have any plants around.

Source: Comet 67P Found to Be Producing Its Own Oxygen in Deep Space by Nancy Atkinson, Seeker

On July 9th, 2017 we learned about

The extreme surface conditions of our post-collision Moon

When a ten-mile-long asteroid hit the Earth 65 million years ago, it resulted in death and destruction on a scale that’s hard to comprehend. When an object the size of Mars hit the Earth 4.5 billion years ago, there wasn’t anything alive to kill, which is good because the amount of destruction was completely off the charts. Both the Earth and the other object, a would-be planet named Theia, were basically reborn in violent swirl of molten rock and metal. In the end, the Earth was left with a new moon born from some of the debris, but it would be at least a thousand years before either body would even resemble the locations we know today.

As you might imagine, smashing two planet-sized objects together creates a lot of friction and heat. In the immediate aftermath of the collision with Theia, it’s estimated that the surface of the Earth was close to 3,632° Fahrenheit, hot enough to melt gold, iron and rock, but not hot enough to start spontaneously welding those metals together. However, the Earth would have still glowed with dim red light like a red dwarf star, and heated one half of the Moon up to 3,092°.

Flowing metal and very fast wind

Being cooked at close range would have made some dramatic changes to the composition of our Moon. Instead of the cold, dusty satellite we now know, the Moon would have been covered in a sea of molten metals like sodium. The metal would have been heated enough to have some material evaporate into a considerable, if temporary, atmosphere. That metal-based air would have been as thick as 1/10th the thickness of Earth’s, and it would have been blowing violently around the Moon at over half-a-mile a second, whipping up waves of liquid sodium in the process.

The reason for the wind is that for as hot as the Earth-facing side of this molten Moon would have been, the opposite side would have been extremely cold. Despite the layer of evaporated sodium, the dark side of the Moon would have been -238° Fahrenheit. As the scorching hot atmosphere blew into the darkness, it would probably have started to freeze, leaving a layer of sodium “snow” as it cooled.

Search for the sodium

The above scenario is based on simulations, but the frozen sodium atmosphere may provide a way to test if this is an accurate model or not. While much of this super-heated atmosphere would have been blown into space, as the Moon isn’t good at holding on to gases, the sodium that quickly froze should be preserved in the rocks and dust. Finding a ring of extra sodium near the transition between the light and dark sides of the Moon would therefore support this model of the satellite’s wild, frenzied origins.

Source: The moon might have had a heavy metal atmosphere with supersonic winds by Lisa Grossman, Science News

On July 4th, 2017 we learned about

Martian water may have flowed thanks to intermittent infusions of methane

In their ongoing quest to understand Martian water, scientists are now suggesting that the Red Planet was once heated by a planetary Dutch Oven. Many geological features on Mars suggest that water once flowed over much of its surface, but scientists are at a bit of a loss to pinpoint how that would have worked with the planet’s thin atmosphere. As far as we can tell, heat from the Sun should have been lost too quickly to warm up the planet’s water, prompting investigations into alternative climate models. One promising possibility may be periodic bursts of methane erupting from the bowels of Mars surface, creating temporary insulation to let the planet warm up.

If this model can be verified, it matches up with existing evidence of shifting temperatures quite well. With all the channels and signs of erosion spread across Mars, it seems that the place was once quite wet, even sporting enough water to support tsunamis. But while there’s little doubt about the existence of these past rivers, lakes and oceans, the timing has never made sense. Dates estimated from impact craters indicate that the water was somehow flowing after most of Mar’s atmosphere had already been lost to space thanks to influences like solar wind. Intermittent puffs of methane can then fill in that hole, providing warmth for these periods when water flowed while never replacing a stabilized atmosphere.

Other models for methane

Mars isn’t burping up a lot of methane today, but there is some precedent for this idea. Saturn’s moon Titan is currently socked in with methane in it’s atmosphere, and the gas helps create a greenhouse effect that traps solar energy close to the moon’s surface. Similarly, Earth’s methane supply does the same thing, working alongside other gases like carbon dioxide to hold onto heat from the sun. Further data is being gathered by the MAVEN spacecraft, and we may see a more detailed model for exactly how warm methane could have made Mars in it’s more liquid-friendly days, billions of years ago.

Source: Bursts of Methane May Have Prepped Ancient Mars for Life by Irene Klotz, Seeker

On June 25th, 2017 we learned about

Simulations sort though how Jupiter and Saturn influence what gets to stay in our solar system

We tend to think of our solar system as “ours,” but it’s easy to see how we’re actually just lucky enough to be in Jupiter’s cosmic neighborhood. The gas giant very likely helped shape our solar system billions of years ago, plowing through debris and dust as it moved to it’s current location near the asteroid belt, making Earth a safer place in the process. While Jupiter’s orbit has settled down, that protective role may carry on, but maybe with a bit of help. Simulations have found that Saturn seems to team up with Jupiter, and the two largest gas giants in our solar system repel or eject a fair number of comets and asteroids that might otherwise intersect with smaller planets, like Earth.

Guarded by gas giants

The idea that Jupiter’s immense size could somehow act as a shield from transiting asteroids or comets originated from an indirect reading of a study that actually focused on smaller gas planets. It was suggested that solar systems with planets no larger than Neptune would likely have more comets around, ejecting fewer objects out of their systems. That invited comparisons to our solar system with out two larger gas giants, and people started assuming that since they were bigger, they must be responsible for the relatively sparse collection of comets and asteroids nearby. The gravitational influence of something the size of Jupiter is huge, and it seemed reasonable to think that it made it into a bit of a bouncer for the solar system. NASA has even used Jupiter’s gravity to help speed up our satellites, and so less carefully aimed asteroids could easily be fired away from other planets’ orbital paths.

Simulating the effects of Jupiter and Saturn

As nice as the internal logic of this model was, it hadn’t actually been tested in any way. Without the ability to drop a few thousand comets into our corner of the universe, researchers turned to simulations to figure out what Jupiter’s bulk actually did to incoming objects. These simulations revealed that while Jupiter was important, it didn’t launch comets and asteroids on its own very consistently. It took the combined influence of Jupiter and Saturn to eject foreign objects, as neither gas giant seemed to be sufficient if the other was removed from the simulation.

A gas giant on its own isn’t without consequence though. The simulation also found that Jupiter’s gravity does a good job of slowing incoming objects down, altering their paths in the process. This means that material from these objects would actually be more likely to end up on the small, rocky planets in the inner solar system, like Earth. This scenario didn’t necessarily mean that Jupiter was putting Earth in harms way, but it might make a difference when calculating how much water on our planet may have been delivered by comets. The ice from these comets is thought to have at least partially seeded our planet with H2O, and it seems like some of them found their way here thanks to a nudge from Jupiter.

Source: Saturn Could Be Defending Earth From Massive Asteroid Impacts by Elizabeth Howell, Seeker

On June 8th, 2017 we learned about

Sizing up a star based on its neighbor’s bent light

For all the things we know about distant stars in the galaxy, we don’t have a concrete measure of how big they are. Just about everything we can measure in a star is based on the light it emits – the color and brightness can tell us about the how hot they’re burning, and what elements they’re made of. Fortunately, it turns out that light from stars can also tell us about their mass, thanks to an idea called gravitational microlensing.

Light warped through gravity’s lens

Gravitational microlensing may sound like filler dialog on a science fiction show, but it’s actually pretty straight forward once you accept that light is affected by objects’ gravity. Similarly to how light is bent in a glass lens, gravity can also bend and warp the direction light travels in, usually in a circular manner around a big object. This idea was first proposed by Albert Einstein in 1936, and the arcs of warped light around massive objects like stars and black holes we’ve since observed have appropriately been named “Einstein rings.” Einstein even went further, suggesting that we might be able to measure the mass of an object by seeing how much it’s gravity bent the light around it.

Einstein’s predictions about measuring mass with bent light weren’t all correct though, as he also assumed that this technique would never actually be of practical use. To measure the mass of one star with gravitational microlensing, you need a second star in exactly the right position behind it to provide the light that will get bent. Even with that star in perfect near-alignment, Einstein assumed that the light would be warped to such a small degree that we’d never be able to detect the difference. Fortunately, the Hubble Space Telescope has proved sensitive enough to do just that, and astronomers were able to successfully see light warping around a white dwarf star 18 light years away from Earth.

White dwarf weigh-in

So how big is this star? It turned out to be 0.675 solar masses, or around two-thirds the size of our Sun (or around 1.342×1030 kilograms). This is actually the second shot at measuring this particular star’s mass, as it was previously calculated by comparing its orbit to that of its closest neighbor. The two stars were thought to be part of a binary pair, which allows for an alternative way to measure the effects of gravity and thus, mass. However, the latest measurement is thought to be more accurate, and it has some astronomers doubting that the two stars are even a binary pair in the first place.

In the future, astronomers will likely further proving Einstein right and wrong about these measurements, as they start relying on them more frequently as technology allows for more and more precise observations of light.

Source: Astronomers measure the mass of a star—thanks to an old tip from Einstein by Daniel Clery, Science

On June 5th, 2017 we learned about

Enormous, incandescent exoplanet glows hotter than some stars

Stars are often compared to fireballs, but a new exoplanet named KELT-9b has been found to make a much stronger claim for that title. The huge gas giant’s atmosphere glows at temperatures around 7,800º Fahrenheit. It zips around its star every day-and-a-half, trailing a tail of red-hot particulate behind it. The only catch to the fireball analogy is that there may not be any actual combustion taking place on KELT-9b. Everything is so hot, a lot of it’s gaseous atmosphere is just metal ions circulating around the planet.

Piping-hot planet

Unsurprisingly, this blazing existence isn’t really sustainable. The heat causes the planet to glow also causes the expansion of the gases in the atmosphere. That might be fine, except that the planet is also incredibly close to the local star, KELT-9, hence that very short year around a considerably-sized star. As a result, the planet’s atmosphere is blasted with enough energy to strip away around 11 million tons of material every second. If that wasn’t enough, over the course of the next 200 million years, the star is expected to expand, eventually reaching the point where it will graze the super-heated atmosphere of KELT-9b. At that point, the planet might be reduced to a small, rocky core that remains in orbit, or be disintegrated and absorbed by the star itself.

In the mean time, a silver, or rather, glowing crimson lining may be on the back of the planet. KELT-9b is tidally locked, meaning it has no day or night cycle. The side of the planet that permanently faces the star reaches the peak temperatures mentioned above, but even the backside remains hot to glow like an ember. Estimates put the “darker” side of the planet at temperatures still exceeding some cooler stars in the galaxy, thanks to the heat distributed by the swirling, metallic atmosphere.

Unusual target for observation

Obviously, this is not the “Earth-like” conditions NASA usually hunts for when looking for exoplanets. KELT-9b was actually discovered using the Kilodegree Extremely Little Telescopes (KELT), devices built using less specialized components to search among hotter stars that typically blind us to the presence of orbiting planets. However, the glowing atmospheric conditions and bulk twice that of Jupiter made it possible to spot KELT-9b as it passed in front of it’s host star. At around 18,000º Fahrenheit, KELT-9 is a hot, bright star which makes observations difficult, but more instruments will be looking at that part of the sky soon to see more details about this bizarrely intense planet.


My second grader asked: Does it have any moons?

Probably not? The first concern is that tidally-locked bodies have a really hard time holding onto their satellites, as things easily spin in or spin out of orbit if the planet isn’t spinning. In this particular case, there’s also the proximity to the star to consider, which might be close enough to scoop up any moons in the area. Finally, spotting a moon 650 light years away around a planet, even a glowing one, it’s easy to do, so we probably won’t see anything around KELT-9b any time soon.

Source: Kelt-9b: astronomers discover hottest known giant planet by Ian Sample, The Guardian

On May 31st, 2017 we learned about

The Parker Solar Probe’s complicated course to cruise through our Sun’s corona

In a little over a year, NASA is going to investigate what makes the Sun so hot. Like many questions associated with rocket science, this is actually a bit more complicated than you might think. For as much as we’ve figured out about the size and structures of stars thousands of light years away, we still have a lot of questions about exactly how our local star functions. To find out more, we’re sending the Parker Solar Probe, which will get as close as 3.7 million miles above the Sun’s surface. If that seems far away, keep in mind that that’s still close enough to sweep through the Sun’s outermost layer, the corona. Which also, incidentally, is where things are at their hottest.

The way the Sun sheds heat is a bit unintuitive. Even though it’s hot enough to maintain a series of fusion reactions in its core, the Sun’s out layers are somewhere where the heat is. The surface of the Sun, called the photosphere, can get to around 10,340° Fahrenheit, which is such an absurd number it’s hard to really conceptualize. However, the layer sitting on top of that, the chromosphere that makes those pretty loops of plasma in photos, can reach temperatures of 35,540° Fahrenheit. Beyond that is the corona, which can kind of be thought of as the Sun’s version of an atmosphere. It’s a less dense collection of high-energy particles, with temperatures reaching over a million degrees. Figuring out the dynamics that make the surface cooler than the outer “clouds” is one of the tricky questions the Parker Solar Probe will be gathering data on once it arrives in orbit next fall.

Arranging the appropriate orbit

Keeping with the whole “complexity” theme, getting the probe to the Sun in the first place will be tricky as well. The Earth is zipping around the Sun at around 19 miles per second, which means that upon launch, the probe will be too. To get closer to the Sun, the probe will need to slow down significantly, flying against the Earth’s orbit so that it can get in closer to our local star. At one point, plans called for the probe to head out to Jupiter to be able to establish a slower orbit, but the current plan calls for a few loops around Venus instead. In the end, the probe will still arrive at the Sun at a screaming 124 miles per second, which is a good way to deal with being cooked in the corona.

To survive this pass through million-degree heat, the Parker Solar Probe will carry a thick heat shield on one end. At only four-and-a-half inches thick, the carbon composite shield is expected to provide enough protection for some very fast passes through the corona, probably benefiting from the fact that heat transfer isn’t an instantaneous process. Most of the delicate, sciencey-bits should be able to enjoy the trip at around room temperature, even if the local weather is quite a bit hotter than that.


My second grader asked: Why is it the Parker Solar Probe?

Yes, “Parker” doesn’t sound quite as exotic as Juno or Cassini, although the motivation is similar to the latter example. Like Cassini, Hubble and other spacecraft, the Parker probe is named after a contributor to our understanding of space. Eugene Parker predicted solar wind before it had ever been measured, and his picture, a few papers and inscription of his choice will be part of the spacecraft’s payload.

Source: Parker Solar Probe: NASA renames upcoming mission to touch the Sun by Jason Davis, Planetary Society