Blogs / Bad Astronomy

The UK newspaper The Telegraph has an interesting slide show of their pick for the top 30 conspiracy theories. Before you ask, the Moon Hoax rated number 4.

I have not heard of many of them, and some shouldn’t even be on the list. Roswell is there, but not UFOs in general. And please, chemtrails? This is one of the lamest CTs of all time, along with crop circles. Feh. But it’s rather fun to read them all in a row. People believe funny things.

Tip o’ the tin foil beanie to James Oberg.

Distance crushes perspective. Objects hurtle through space at mind-numbing speeds, some moving so quickly they could cross the United States in just seconds; yet, due to their distance, we could wait thousands of years to be able to perceive their motion at all.

Unless, that is, they leave behind some tell-tale sign of their rapid movement. Space is not empty, and a star plowing through this ethereally thin gas at dozens of kilometers per second reveals itself. The gas gets compressed ahead of the star, and flows around it in graceful arcs. Like water flowing around the bow of a ship, such a formation is called a bow shock.

This shock wave can be invisible to the unaided eye, but when we train infrared telescopes on them they leap out of the picture. Behold the bow shock of Betelgeuse:

This picture was taken by the Japanese satellite observatory Akari. It’s a composite of images taken at 65 (blue in the image), 90 (green) and 140 (red) microns. These are well beyond the human eye’s capacity to see; our sensitivity is about 0.3 to 0.7 microns.

Betegeuse is a red supergiant about 400 600 light years away (in the linked article, it’s mistakenly listed as 200 light years). As the superstar plows through the gas between stars (the interstellar medium, as we pros in the know like to call it), the gas forms a bow shock about three light years across. It’s not the physical star itself doing the compressing, it’s actually Betelgeuse’s stellar wind. Like our own Sun’s solar wind, Betelgeuse blows off a stream of particles, but it’s far denser. The expanding gas is what’s slamming into the interstellar medium and forming this beautiful structure.

I have never seen anything like this from Betelgeuse, and it’s incredible. The shape of the bow shock makes Betelgeuse’s direction of motion obvious enough. The star is moving about 30 km/sec across the gas, and the wind is expanding at about another 17 km/sec, so the collision is actually pretty fast on human scales, but relatively weak for such events (sometimes objects are ramming through gas at hundreds of km/sec).

Besides being a pretty picture, there’s science to be had here. Examining data like this can tell us how thick the matter is between stars near Betelgeuse, and how it behaves when smacked by an expanding star’s wind. One day, Betelgeuse will explode^*, going supernova, and the matter from the explosion will expand and slam into the already-ejected material at a large fraction of the speed of light. Understanding that material before the star explodes helps us understand what happens after it explodes, and that in turn teaches us a lot about the way stars are born, live out their lives, and die. Considering we owe our existence to such supernovae — they created the iron in our blood and the calcium in our bones — I think that’s a field worthy of study.

Cosmic rays are subatomic particles streaming through space at almost the speed of light. They are actually different kinds of particles, including protons and helium nuclei (two protons and two neutrons bound together). Their exact speed determines how much energy they have; a faster particle is said to have higher energy (or conversely a higher energy particle is moving more quickly).

Many cosmic ray sources have been identified. Most appear to get their start in the expanding debris of a violent supernova explosion. Shock waves rip to and fro in the material, and particles trapped in the gas can be accelerated to phenomenal velocities.

But there’s a problem: the higher the energy of the cosmic ray, the more its travel through the galaxy wears it down. A relatively slow-moving cosmic ray has no difficulty traveling millions of light years (coming, for example, from supermassive black holes in the centers of other galaxies), but the faster they move, the more they are at the mercy of forces like the intergalactic magnetic field. Extremely high-energy cosmic rays can’t travel very far before having their energy sapped away.

However, a new study using the balloon-borne instrument called the Advanced Thin Ionization Calorimeter (ATIC) shows that there is an excess of particles coming in with energies of 300-800 billion electron Volts. To give you an idea of the energy involved, a photon of visible light has an energy of 1 eV. So these puppies are screaming in with billions of times the energy of light we can see (note that light is not a subatomic particle; this is just to give you an idea of the energy). In fact this is thousands of times the energy of even X-rays.

Cosmic rays at this energy should slow down so much that the source of these particles can’t be more than 3000 or so light years away. That’s pretty close, on a galactic scale (the Milky Way is 100,000 light years across). Whatever the power source for these particles is — a pulsar, a black hole, or something more exotic — it’s practically in our back yard.

Anything that close capable of producing such prodigiously propelled particles should, I would think, be relatively easy to find. I have not heard of anything that close, however. The scientists who conducted the study therefore have an alternative idea: dark matter. One possible candidate for this mysterious matter that fills the Universe is a type of particle that, if it collides with another dark matter particle, can produce cosmic rays in this energy range. That’s still speculative, but it’s awfully interesting. Since dark matter permeates space, the cosmic rays could be coming from pretty close by; even inside the solar system!

That’s pretty weird to think about.

It’s too early to speculate much about them. ATIC only detected the particles, but is not sensitive to direction. If a detector were used that could see where these cosmic rays were coming from, that would give a big clue to their origin. If they all come from one spot in space, for example, then we know it’s probably a black hole or pulsar. But if they come from everywhere, well, wouldn’t that be interesting?

Last week, I wrote about NASA Administrator Mike Griffin, and how he may be replaced when Obama takes office. Given that he was a Bush appointee, I imagine he must be thinking he’s on his way out as NASA’s top banana. That may explain why he made a public statement aimed at Obama about NASA’s future.

Basically, he said that the incoming Administration needs to stick with going back to the Moon, and that backing down from such an endeavor would be a mistake. After commenting that he would be honored to continue on with NASA if asked, he said:

“Two successive Congresses - one Republican and one Democrat - have strongly endorsed the path NASA is on. I think it’s the right path,” Griffin said.

“For 35 years since the Nixon administration, we’ve been on the wrong path. It took the loss of (space shuttle) Columbia and (the accident investigation) report to highlight the strategic issues to get us on the right path,” he said.

“We’re there. I personally will not be party to taking us off that path. Someone else may wish to, but I do not.”

That’s a pretty strong statement, and makes clear his thoughts (refreshing from someone in charge of a government agency). I happen to agree with him; going back to the Moon is what NASA should focus on, as long as the science is not sacrificed.

The caveat here is the economy. If we lapse into a depression, then NASA may be the first on the chopping block. But I hope that’s not the case; NASA employs many thousands of people, and letting them go would be a huge mistake, both economically and for the future of the nation.

Also, the rockets that take us to the Moon will be capable of vastly larger payloads than we can currently loft, making solar system and deep space science easier. Look at what the Cassini Saturn probe is doing, and then imagine launching much larger probes with far more capabilities than we have now… going back to the Moon can benefit all of space exploration and science if done properly.

Personally, I think Griffin will be replaced, and I don’t have a clue who might be the person to take over. But I do hope they listen carefully to what Griffin has to say. Some of what Griffin has done in the past needs to be forgotten (or maybe even apologized for), but on other topics he’s right on the money.

I have managed to pull a muscle in my shoulder, so writing is really hard today. Until I can make my left arm move normally, I will simply leave you with this incredible image of Gamma Cygni, a bright star in the summer constellation of Cygnus.

The image is by Davide De Martin of Sky Factory. He takes archived professional astronomical images and makes these gorgeous mosaics of them (go to the link, his image is zoomable!).

In this picture, the star appears to be surrounded by warm, glowing gas. I looked up what type of star Gamma Cygni is, and was surprised to find out it’s an F star. That makes it hotter than the Sun, but not nearly hot enough to make this kind of gas glow! I was relieved to see that the star is actually coincidentally in the foreground. It’s less than 1000 light years away, but the gas cloud is 3-6 times more distant. It’s being lit up by hotter stars inside it.

You should really spend some time looking at the other images David has done. They’re stunningly beautiful, and a fine way to appreciate the majesty of the heavens.

Update: if you like this story, please Digg it!

Does this map show an ancient ocean floor on Mars?

A map of Mars showing the location of possible ancient ocean. Credit: U. Arizona

New evidence says "maybe". But it’s a pretty good maybe!

It’s been argued for years that Mars may have once had oceans of water, billions of years ago. Some catastrophe dried them up, making the evidence for them difficult to detect. Topographic (relief) maps look like there may have been two oceans in one spot, for example, separated by some time. There appear to be two separate shorelines, with one smaller, later ocean existing where there once had been a much larger ocean.

But that’s circumstantial. More direct evidence is needed.

So some scientists speculated a bit. Rocks containing elements like potassium, thorium and iron would get made in the highlands (near volcanoes), then get transported down into the lowlands. If there were an ocean there, those elements would get leeched out of the rocks by the water. Then, when the water evaporated, those elements would be deposited in a thin layer on the surface.

On board the orbiting probe Mars Odyssey is the Mars Gamma-Ray Spectrometer, a device which can measure the abundance of elements on the Martian surface. When it was trained on the lowlands of Mars, it found evidence to support the existence of those oceans! The elements in question were most abundant below the shorelines, as expected, when compared to regions outside (above) the shorelines. The regions with higher concentrations of potassium are marked in red and yellow in the map above, right where the lowlands are.

While this doesn’t prove an ocean as big as the United States once occupied a large chunk of Martian real estate, it’s further evidence of it. Scientists are still arguing over whether Mars had long-lasting, ponded water, or if it was released in short, transient events, only to evaporate quickly away. But either way, we’re not arguing over whether Mars had water, just how long it lasted.

Either way, Mars is an incredible planet. It may have once been much more Earth-like, but then something went wrong. Maybe it was the formation of the giant volcanoes (indicated by the red arrows in the above image), or the loss of its magnetic field that exposed its atmosphere to erosion by the solar wind. As we study Mars more, we get closer to figuring this out. And make no mistake: knowing where Mars went wrong gives us great insight into our own planet. If you think we’re wasting money on researching Mars, then I suggest you take a cold, hard look at that cold, hard planet, then look out your window at our own home world.

There but for the grace of science may go us.

This is seriously weird on a lot of levels.

The guy I morph into is Tom Baker, the actor who played The Doctor back when I started watching it as a kid. I loved his Doctor, so it’s a little odd to see me turn into him… especially without any background music or regeneration effects. But especially especially because of his hair.