Hannibal the T-Rex

Posted on October 17, 2010 by danielfeldman

There has been recent evidence that the Tyrannosaurus Rex, one of the most fearsome carnivores of all time, could have been a cannibal! Nicholas Longrich, a researcher at Yale, discovered large gouges on the toe of a T-Rex from 65 million years ago, and realized that while any large carnivore of that time could have made such marks, the Tyrannosaurus Rex was the only such carnivore in Western North America at that time.

Photo above of a toe bone, and the gouge that is thought to only have been able to come from a T-Rex. Credit to Nicholas Longrich of Yale University.

After discovering the initial bone with such markings, Longrich and his collaborators examined similar specimens from various museums, which include the Museum of the Rockies, University of California Museum of Paleontology, and the American Museum of Natural History, among others (No, these dinosaur bones do not come alive at night–I’ve been there past sundown). In total, 17 specimens were identified as having these marks, 4 of which are identified as being Tyrannosaurus! According to sciencedaily.com, this represents “a significant percentage.”

The Majungatholus, an abelisaurid, is the only dinosaur prior to this discovery known to be a cannibal. Longrich thinks, however, that “the practice was likely more common than we think and that closer examination of fossil bones could turn up more evidence that other species also preyed on one another.”

The T-Rex could weigh up to 10,000 kg (to compare, the siberian tiger, which is the largest living land dwelling “hyper-carnivore”, weighs up to 300kg), so if they got into a fight and one killed the other (and who hasn’t wanted to kill someone?), it would have represented quite a bit of free meat. In fact, cannibalism is very common among large carnivores. Additionally, there’s no evidence that dinosaurs had a set of morals, so it’s not like they’d be against eating each other out of a sense of ethical standards. Humans, who arguably have morals, have succumbed to eating each other sometimes as well–and no, I’m not referring to Sweeney Todd. So it’s not an absurd notion that the Tyrannosaurus could join the ranks of the cannibals in Earth’s long history.

As of right now, scientists are unsure of the true eating habits and patterns of the T-Rex, but it’s a topic that many paleontologists are hoping to answer, considering it would be totally different than any living animal today. The problem is, there is very little direct evidence of its eating pattern. This discovery could be a piece in the fascinating puzzle that encompasses the most famous dinosaur. To read more, Longrich’s paper http://www.plosone.org/article/info:doi/10.1371/journal.pone.0013419 is online!

Posted in Biology | Tagged , , | Leave a comment

Pluto is Not a Planet!

Posted on October 13, 2010 by danielfeldman

As an aspiring astronomer/astrophysicist, I am often asked why Pluto is not a planet. I also get many defiant people telling me they know better than we scientists, and that Pluto is without a doubt, a planet. Well, I have to be honest with you all. Pluto is not a planet. Sorry for the length, but now you’ll know why you’re wrong if you’re shaking your head at this first paragraph in dismay. It’s for your own good, trust me.

After reading The Pluto Files by Neil deGrasse Tyson (I had to, he works a few doors down from me), I have become further convinced that when it comes to planets, Pluto is pretty pathetic. Why? Well, before I get into the “official” definition of a planet, let’s just discuss some properties of everyone’s favorite underdog. First, let’s discuss size. NASA’s Jet Propulsion Laboratory has a measured a radius for Pluto of 1137±8 km—to give some perspective, the radius of the moon is roughly 1737 km, 600 kilometers larger! It’s also about 1/5 of our moon’s mass.

Continuing on size, Pluto has a moon (3 actually, but two of them are really wimpy) Charon, whose size is not much smaller than Pluto. You might think, “Well, Pluto has a moon, so clearly that’s planet-like.” Indeed, you might think that, but it’s more of an embarrassment than a triumph for Pluto. Charon is so big compared to Pluto that the two objects are more of a double-system…this means that they orbit around a point in between the two of them, rather than Charon going around Pluto. Additionally, both Charon and Pluto are “tidally locked” to each other. This means that the same side of Charon alway faces Pluto, and vice versa. This effect is seen with our moon—the same face of the Moon always faces Earth (although Earth is not tidally locked to the Moon, so we see it rise and fall in the sky just like the Sun).

Unlike other planets, Pluto has a very eccentric elliptical orbit, and is inclined out of the plane of the solar system; this is something that none of the planets share with Pluto. Pluto is also more like a comet than it is a planet—it is believed to be around 30% water ice, and if it was placed near the Sun, it would have a tail, just like a comet. If it was placed where Mercury is, it would disintegrate!

Convinced yet? Well, controversy started to stew once a slew of large objects similar to Pluto began to surface in a region known as the Kuiper Belt, at similar distances to Pluto. These objects were very similar to Pluto, and it was hard to decide what to call them. Should they also be planets? Should they be super comets? It didn’t help when one of them, Eris, was found to be even larger than Pluto! That’s right, sink this in—Eris is larger than Pluto. It was soon clear that something had to be done.

The final nail in the coffin came in August of 2006, when the International Astronomical Union redefined the word “planet”. Planets now had to meet 3 criteria (direct quotes)…it must be a celestial body that:

  1. is in orbit around the Sun.
  2. has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and
  3. has cleared the neighborhood around its orbit.

Pluto meets the first two criteria—it is orbiting the Sun, and it is nearly round (hydrostatic equilibrium shape means that its gravity is felt roughly the same anywhere on the surface, and so it is nearly spherical. This is why all massive celestial objects with high gravity are round). But Pluto has not cleared its orbital path, which means that if you add up the mass of all of the objects in its vicinity, the mass is significant compared to that of Pluto’s mass. So what does this mean? Like all the recent large Trans-Neptunian Objects (large objects past Neptune) discovered, Pluto is now a dwarf planet.

Ceres, a large, round asteroid in the asteroid belt, was bumped up. Interestingly, according to Tyson’s book, Ceres was once a planet! When it was discovered that many asteroids, of similar properties as Ceres, existed in the same area, Ceres was demoted to being king of the asteroids. Sound familiar? Well, nobody complained about Ceres, but there was quite a uproar from the community over Pluto’s demotion.

Convinced yet? You should be. Pluto is now, so we think, where it belongs, and it shows you that science is ever evolving as we learn more about objects in our Universe. Indeed, progress is good, not bad. We may have “lost” a planet, but we gained a whole bunch of new, awesome objects in our own backyard, and I think it’s something to be celebrated.

Some size comparisons, courtesy of NASA, ESA, JPL, and A. Feild (STScI). I think the resolution of some of these images may be misleading. The key is to note the size comparisons. Also, read Neil’s book—it’s good.

Posted in Astronomy | Tagged , , | 1 Comment

Earth 2.0?

Posted on October 5, 2010 by danielfeldman

I recently have encountered a firestorm of people (friends and family, naturally) asking (or telling) me about the big news to recently come out of the astronomy newsletters. “Another Earth has been found,” I get told with much excitement. Yes, we have found a fascinating world, extremely close to home and which may be able to harbor life. But before we all jump the gun, the truth is that we MIGHT have discovered such a planet. Still, it’s a really interesting place worth noticing, so here’s a quick rundown of the discovery.

Earth 2.0 (as I like to call it), is orbiting around an M Dwarf star, which is astronomy’s way of saying a small, red, dim star that is much cooler than our sun. This star is called Gliese 581, and since this is the 6th planet around this star, the planet is called Gliese 581g (the first planet discovered is Gliese 581b, and it goes down the list alphabetically in order of discovery). Despite its bland name (I mean, it’s hard to compare to rock-solid names like Earth and Mars), Gliese 581g might be the coziest place for humans to go if we ever lost Earth. Orbiting at roughly 14 million miles away from its star (closer than Mercury is to our Sun), Gliese 581g is in what is referred to as the Habitable Zone, or “Goldilocks Zone”—not too cold, and not too hot. It is in this zone that liquid water is able to exist as its natural state. So far, only one planet has ever been confirmed to have this ability—Earth.

The Gliese 581 system, compared to the distances of our own inner solar system. Image courtesy of the National Science Foundation.

“But Dan, we orbit the sun at a distance of 93 million miles. How come the ‘Goldilocks Zone’ for our sun is so much farther than the zone for Gliese 581?” Great question, reader! The reason is actually very simple—our sun is hotter than Gliese 581, and so its Habitable Zone is much farther away than the one for Gliese 581. But being a cooler star is not a bad thing—stars such as Gliese 581 fuse hydrogen at a lower rate than other stars (they don’t run out of fuel as fast), allowing them to have extremely long life spans. In fact, no M Dwarf star has ever died out, and even after a trillion years (the Universe is only about 14 billion years old), they will still be alive and thriving! These stars have a soft spot in my heart, since I currently do research on them.

Why else does Gliese 581 excite us? It’s so close! Located in the constellation Libra, it is approximately 20 light years away. Of course, that’s 6 trillion miles away, but in our galaxy, whose diameter is 100,000 light years across, it’s literally our next door neighbor (ok, maybe about 2 or 3 houses away). At our current technological abilities, we will have no way of getting there. But who knows what the future holds.

Keep in mind, however, that Gliese 581g is still not confirmed to contain life, or even to contain liquid water at all. Scientists currently estimate an average temperature on this planet between 10 and -24 degrees fahrenheit, comparable to summer in Antarctica. Still, Gliese 581g is tidally locked to its star (the same side of the planet faces the star all the time, while the other side is permanently dark), so temperatures can vary wildly depending on what side you’re on. In fact, being 3 or 4 times the size of Earth, this planet may not be habitable at all. Indeed, conditions for life on a planet is complicated and based on many factors, so it’s very difficult at this time to really say what’s going on there.

Still, there’s a chance, and that’s exciting! In years to come, we should hopefully be able to find out more data about the planet (atmosphere, composition, density, etc.), as well as confirm the data we think we already know (size, temperature), and once we find out that data, we’ll be able to truly form a picture of what this planet may be like. Who knows…maybe this distant world is a kindred spirit to our own, blue paradise.

Posted in Astronomy | Tagged , , | 2 Comments

Gigantic Jet Captured on Film!

Posted on October 3, 2010 by danielfeldman

My astronomy professor alerted me to this website today: http://spaceweather.com/archive.php?view=1&day=01&month=10&year=2010

Recently, Joel Gonzalez recorded a rare phenomenon known as a gigantic jet near Kennedy Space Center. For those of you who watched the video in the link, you might be thinking “well, that’s cool, but it lasted only a second or so.” True, it’s hard to appreciate the magnitude of the gigantic jet based on the video, but don’t be fooled–this is some awesome science at work!

When we think of thunderstorms, we think of two things–the first is thunder (obviously) and second is the brilliant event that can spark thunder in the first place–lightning. Lightning is a large discharge of electrical energy in the atmosphere during a thunderstorm, or sometimes during volcanic eruptions or dust storms, which can also build up static electricity. During a thunderstorm, lightning bolts can erupt out of the bottom of the cloud and even hit the ground at supersonic (faster than sound) speed, which is why you hear thunder afterwards (the sound is too slow to keep up, and so there is a delay). But what about at the top of a storm?

This picture, a representation of upper atmospheric electrical effects (from wikipedia, I know, but it’s still good) shows just how awesomely large these effects are. And the names of these events are pretty funny–I’d love to know who named these events “elves” and “sprites.”

A sprite (as seen in the picture) is triggered by “a discharge of positive lightning between the thundercloud and the ground.” These sprites happen in clusters, and can not only be that brilliant reddish orange color, but also greenish blue. Less common are the blue jets (also shown in picture), which are conical projections coming up from the top of the cloud, making it appear similar to lightning in the opposite direction, but thicker, longer, and brighter. Even rarer (so we believe) are gigantic jets, which Gonzalez captured on video; these jets are similar to blue jets, except they reach twice as long (up to 50+ miles high into the atmosphere–for perspective, the Empire State Building is about 1/4 of a mile high), and have only been recorded a handful of times, especially in storms over water. Blue jets in general aren’t like sprites in that they are associated with lightning strikes. Instead, they may be associated with strong hail! They are also much brighter than sprites, and last roughly one second. They weren’t discovered until 2001, and since they are usually seen over ocean storms, it’s amazing that Joel Gonzalez was able to capture this gigantic jet at all!

These gigantic jets are believe to contribute somehow to a flow of electricity around the entire planet, but details are fuzzy. According to the San Francisco Chronicle, it’s like a river of electricity around the globe, and sometimes, “like a bursting dam,” the energy can explode out in the form of lightning, sprites, elves, or jets (or a combination, of course!). I highly recommend looking into the study of electricity in the atmosphere, it’s fascinating stuff! I know the study of lightning is called “fulminology”, but I’m not sure if these events are lumped together into that field. Hopefully now, you’ll have new sense of excitement when watching that video, and any other video showing (or seeing from your window) an active thunderstorm! What you see is, in truth, awe inspiring.

Posted in Physics | Tagged , , , | 1 Comment