Oh, this is very cool: two astronomers think they may have found meteorites from the fireball that roared over Texas last week.

They found two small pieces matching a description of meteorites (they had a blackened surface, called a fusion crust) in a town called West, between Waco and Dallas, which looks to be right along the fireball’s path.

If this pans out it will be very exiting! With all the eyewitnesses and the video, a good orbit for this object may be backtracked. And now, if this pans out, we’ll have samples that can be examined chemically to determine the fireball’s composition! It’s the next best thing to going to an asteroid itself, so this is could turn out to be a major boon for astronomers who study asteroids and meteorites both.

And not only that, this thing that came in was probably a meter or so across, which means larger chunks might be out there, just waiting to be found. I hope some folks in that area go looking!

Tip o’ the ten gallon Whipple Shield to BABloggee Lowell Vaughn.

500 light years away, the star T Leporis is dying.

It used to be much like the Sun, but the store of nuclear fuel in its core is running out. Due to the nuclear processes going on deep inside it, its energy production has vastly increased, blasting out thousands of times the energy it did when it was a stable star. The outer layers of the star absorb this energy, and, like a hot air balloon, expand hugely. Even though it is now far, far brighter than it used to be, the expansion actually cools the star’s surface. It has become a bloated, swollen red giant.

Because the surface is cooler, more complex molecules can form there. What astronomers call dust, they are blasted by the intense brightness of the light coming up from below. And because the star has expanded so much, its gravity at the surface is much lower, too. The huge force upwards from the light cannot be held back by the feeble gravity, and the dust is launched into space, creating a spherical shell around the star.

And now, for the first time, astronomers have taken the sharpest infrared pictures ever of that shell as it is hurled into space.

The image above is not an illustration, it’s an actual image of a red giant star undergoing dying paroxysms and blasting a dense shell of molecules into space. As you can see by the comparison drawing of the Earth’s orbit around the Sun, T Lep has expanded to a diameter of nearly 300 million kilometers (180 million miles). At first, I thought the ring around the star was not real, and was instead what’s called an imaging artifact; a mirage due to optical effects inside a telescope or camera. But it’s actually the dense shell of ejected material from the star.

This incredible picture was not taken by a single telescope. It was produced by combining the light of four different 1.8 meter telescopes in a process called interferometry. It’s a fiendishly complex process that virtually creates a telescope that has the same resolution (ability to see small objects) as a single telescope spanning the separation between the smaller ones. In other words, separate the smaller ‘scopes by 100 meters, and you can create a virtual telescope 100 meters across.

The longer the wavelength, the easier this process is (though it’s never easy); in this case the image was taken in the infrared. It took multiple observing sessions over several nights, but in the end the astronomers were able to see objects as small as two milliarcseconds across– much smaller than Hubble can resolve, and equivalent to an object just four meters across sitting on the Moon’s surface!

The ESO created a cool zoom-in of T Lep, starting just south of Orion and ending with the super-high-resolution image:

This superior resolution can allow astronomers to determine the size, shape, density, and structure of the stellar wind blowing off the surface of T Lep, which will help them understand how stars like this die.

And by "stars like this", I mean stars like the Sun. Some day, about 6 to 7 billion years from now, our Sun will run out of hydrogen in its core and swell up into a red giant just like T Lep has. Take another look at that image; see how the surface of the star is almost touching the size of the Earth’s orbit? We don’t know exactly how big the Sun will get, but that size right there is a pretty good guess. What happens to the Earth at that point is fairly clear, and the news won’t be good.

The Sun’s clock is ticking. It has a lot of ticks left, but the number is finite. Studying stars like T Lep let us take a peek into our own distant future, and techniques like infrared interferometry make sure that the glimpse we get is ever-more sharply focused.

If you want to learn more about how the Sun will die, then read Chapter 7 of my book, Death from the Skies! You’ll get all the details, maybe more than you want.

Photo credit: ESO/J.-B. Le Bouquin et al.

I’ve been reading the io9 scifi blog since they started, and met contributers Annalee Newitz and Charlie Jane Anders at Comic Con last year (where I taped their interviews with various scfi celebs — Jewel Staite, why won’t you return my calls?), so it fills my heart with joy and squishiness when they link to me, like they did yesterday about the Lone (shooting) Star. Yay! They do post a lot of space info along with the scifi stuff, so it’s worth your time to read it. It’s in my feed reader and I check it out every day. So should you.

Fox news (I know, I know) out of Dallas/Ft. Worth Texas is speculating that a small grass fire may have been caused by the fireball yesterday. I doubt it, though. Watch the video first.

First kudos to the news for finally saying that the fireball was not due to the satellite collision. Even then, there’s still some confusion: MSNBC online reports it wasn’t from the satellites, but MSNBC TV has video of reporters speculating it is; some debris has been found, but since I’m positive the fireball is unrelated to the satellites, the debris is probably just something that blew around from a construction site or something and onto a field:

That pipe in the field doesn’t look quite damaged enough to have fallen through the atmosphere at Mach 20, don’t you think?

I’ll add that some in the mainstream media are crowing a wee bit early and incorrectly about all this, like this guy who says that bloggers and twitterers all got it wrong… hey dude, not all of us did.

However, the fire in the Fox video is most likely coincidence. Meteorites are generally not hot enough to start fires when they impact. They slow down to subsonic speeds quickly (which is why the outer parts get so hot and they glow), but then take several more minutes falling through frigid air before hitting the ground; plenty of time to cool off. You need a pretty big object to start a fire, and that would leave an impressive crater. Most likely the fire is a coincidence.

If they do find meteoric debris in that fire after they investigate it, it’ll be in the news. But I bet if they don’t it’ll be relegated to some back page of a newspaper someplace. We’ll see.

I’ll add that even though I have slowly but surely had a growing contempt for much of old media, this event has prodded me further along. Somehow, covering this event faster, more accurately, and better than any newspaper or local news station, but still being made fun of for being just "a blogger" doesn’t make me feel confident that a lot of the people still entrenched in the old media have a clue about teh intertoobz.

Present company excluded, of course. The folks at Discover Magazine get it, and I’m glad they do.

Tip o’ the Whipple Shield to Patrick R. Mullen and Fark.

Go ahead. Watch this video, and try to imagine our former President saying these words. I dare you.

I think he’s serious, and I think he’ll make sure these words become reality. But it’s up to us to hold him to his promises.

Tip o’ the lab coat to PZ.

This is incredible: Australia has eliminated the risk of large measles outbreaks for the next few years. At least, this is the prediction based on past cases, and by lowering the age for children to get the second inoculation from four years old to 18 months.

In 2005 and 2007, Australia had less than one case per million people. 2006 had an uptick with 6 cases per million, but half those cases are claimed to be attributed to an "outbreak linked to the tour of a foreign spiritual group".

Spiritual group, eh? Hmmm. Antivaxxers? Bet on it.

So it’s predicted that large outbreaks will be eliminated. They’ll have fewer than 100 cases per year across the continent, and those will be due to unvaccinated foreigners, who love to ruin everyone’s day. The key here is to maintain the number of people getting the second shot, so that herd immunity rules the day and outbreaks are minimized or eliminated.

Australians continue to amaze me. They do seem to be infected with our own nuttiness — creationism is getting a toehold there, for example, and homeopathy is a plague — but in general they seem to be a pragmatic and bonzer group of blokes.

Australia: good on ya!

Tip o’ the syringe to Dr. Joe Albietz.

So my blog post from earlier about the Texas fireball is now a bit of a mess from all the updates, so I thought I’d post a cleaner version of what’s going on now.

1) A tremendous fireball — also called a bolide, or a very bright meteor — was seen in southern Texas on Sunday, February 15th, just before 11:00 a.m. local time. Many people have described it as very bright, small, and moving rapidly.

2) A video of the fireball has been released, taken by a person videotaping a footrace. The video matches the description of many eyewitnesses.

3) Some people have attributed this event to debris from the two satellites that collided over the Earth last week. I was initially very skeptical of this, then relented a bit. Now I am sure it was not debris from the satellites. Why? OK, that deserves it’s own number.

4) The video shows the fireball to be moving very rapidly. Typically, meteors come into Earth’s atmosphere at 20-50 km/sec (though they can be moving much faster), and burn up 50-100 km high. Man-made space debris re-entering is moving at slower than orbital speed so the max speed is about 8 km/sec. It also burns up lower, and generally you can see flames and whatnot coming off.

I’ve seen man-made debris re-enter, and it’s very different than natural meteors. The difference in speed is very obvious. Right there, that’s enough to make me think this was a single natural object.

It’s possible to get collisional debris moving more rapidly, but it’s difficult. The two satellites closed in on each other at about 10 km/sec, and any shrapnel from that event would most likely be moving at roughly that same speed. If one satellite slammed into, say, an antenna first, then the lower mass antenna might get a pretty hefty acceleration from it, but the amount of energy dumped into it would most likely turn it into a bunch of teeny pieces (remember, the energy of impact was like several tons of TNT). A small object would not have been as bright as the fireball seen.

Also, you’d have to have a pretty special set of circumstances to get any debris from the satellites to re-enter our atmosphere so soon after the collision. It’s far more likely that it will be months before we see any of that shrapnel burning up.

So all in all, I am pretty sure what was seen was natural: a rock or a piece of metal from an asteroid.

5) A fireball was reported in Kentucky Friday night. It’s unlikely these two events were related; if the Texas bolide were from a natural object, then it was a totally different object that entered over Kentucky. At a speed of, say, 20 km/sec, the two objects would have been separated by more than 100,000 km, making a connection pretty far-fetched. And if they were from the satellite collision, again being separated by a day makes it unlikely they were connected.

6) This was certainly unrelated to a NORAD warning of a Russian booster re-entering, which later was determined to have fallen near Africa.

7) There were reports that an FAA official had confirmed this object was from the satellite collision. But those reports never gave a name! When a report came in naming Roland Herwig, he was quoted as saying it was possibly from the collision. Still the false confirmation spread like wildfire via Twitter, when a popular breaking news account stated it as fact (no provenance was ever given for that quotation). Rumors spread rapidly, truth far more slowly.

Also, why the FAA? They are not the go-to agency for this. NORAD would make far more sense, since they specifically track such things. And there was no warning at all from them, indicating once again this was not from the satellite collision. Any piece big enough to be bright enough to be seen in broad daylight is big enough for them to have been tracking for some time.

Conclusions:

This was a fascinating event, both astronomically and socially. I received an email less than an hour after the event from a reader (who, wonderfully, gave both his exact location and the direction to the fireball) as well as a tweet about it. Within a few minutes I had a post up and tweeted about it myself. I started to receive dozens of tweets over the next hour (I’m not sure how many total, but probably well over 100) with information. After an hour or so the misinformation (FAA officials, satellite debris, etc.) started coming in. Someone posted on iReport their own description, and added a photo of a totally different event as an example, and at least ten tweets referred to it as the actual Texas fireball.

Using various websites that track keywords on Twitter helped enormously. I could look for "Texas" and "fireball" and "satellite". That was tremendously helpful.

As info came in I updated the blog post, but that was awkward. Tweeting info is fine, but a more permanent and easily-accessible repository was needed. Now, after the fact, I can collate that info and make a more linear post. If someone has a better way to collect, disseminate, and store breaking astronomical news, I’m all ears. Between the blog and Twitter I think this went pretty well, with a minimum of bad information being spread.

As time goes on I’m sure more video and pictures will surface. I’ll post links to those as I find them. My personal thanks to everyone who saw this event and tweeted, or left comments. This was very exciting!