Review: Men in Black 2

I did not love this movie.

I'm not sure what went wrong between the first movie, which was wonderful, and this one, which was passable, but nothing special. Somehow, the charm and irreverence of the first movie was gone this time around.

Be that as it may, this one had fewer real references to astronomy, but what it did, it got wrong. Oh well. Let's get this over with.

Bad:
In the beginning, we see a montage of aliens blowing up planets. A beam weapon is fired, and the planets explode in giant pieces.

Good:
It's really hard to blow up a planet! It's possible that the alien technology did something like cause a chain reaction which totally disintegrated the atoms, or something like that.

But that's no fun. Well, it might be fun, but really, how much energy does it take to blow up a planet? I did this calculation once before, to show that a comet impact could not destroy a planet. To blow up a planet, you have to overcome the gravity of the planet for each piece. Let's put it another way: Imagine taking a rock and throwing it up so hard it escapes from the planet entirely. For the Earth, that means you have to give it a pretty big velocity, about 11 kilometers per second. It takes a lot of energy to do that, the amount of which depends on the mass of the rock and the amount of gravity you are fighting. Now take another rock, and do it again. And again. And againandagainandagain. Repeat for a gazillion times. If you do it enough times, the planet is gone. You've destroyed it. Congratulations!

It's possible to calculate that total energy you expended. It's called the gravitational binding energy, and is basically the amount of energy locked up in the planet's gravity. I'll spare you the math (but you can find it here if you'd like), but for the Earth that energy is roughly 10³⁹ ergs. An erg is a tiny unit of energy, but 1,000,000,000,000,000,000,000,000,000,000,000,000,000 is a lot of them! For comparison, the Sun puts out about 4 x 10³³ ergs every second, so the amount of energy needed to vaporize the Earth is about the total amount of energy the Sun emits in 3 days! That's a whole lot of energy. I doubt a single ship could generate that much. But who knows? They're aliens!

Bad:
One alien was imprisoned by the Men in Black for stealing our ozone (and presumably creating the ozone hole). He says, "They're very touchy on this global warming thing".

Good:
Arg! The destruction of the ozone layer and global warming are related, but not the same thing! Global warming is due to greenhouse gases like water vapor, carbon dioxide and methane, which trap heat very efficiently in our atmosphere. That causes the planet to be warmer than it normally would be (see my seasons page for more info on this, near the bottom of the page).

The ozone hole is caused by chemicals like chlorofluorocarbons, which break down the ozone molecule. Both global warming and the destruction of the ozone layer can be traced to what amounts to mankind's pollution, but they are very different beasts.

And to prevent the flood of email from people who want to berate me politically for saying we are causing global warming, I will say:

• Some amount of natural global warming exists. Without it, the Earth would be a giant iceball. Again, see my seasons page for more info.
• Like it or not, we are pouring greenhouse gases into the atmosphere.
• Even the U.S. government, which lately has been pretty pro-business, has admitted that global warming is a reality.

Bad:
Near the end of the movie, which takes place in New York City, we see a shot of the sky, which is filled with stars.

Good:
This is a common scene in movies, but it's wrong. From near a brightly lit city, the stars are almost completely washed out by the city lights illuminating the sky. This is called light pollution, and is a pretty big problem for astronomers. When the sky is lit up, faint objects -- and most things in the sky are pretty faint -- are completely overwhelmed, making them extremely difficult to observe.

As an example, when the Palomar Observatory was built, the designers decided that about a hundred miles away from Los Angeles would be a good site. Now look: since that time, the sky has been ruined by the huge city, and the observatory (which housed what was the largest telescope on the planet for decades) now has to struggle to do scientific research.

The problem got bad enough that an organization was founded to help educate people about it. The International Dark Sky Association promotes smarter lighting systems, which are not only safer for people (they tend not create deep dark shadows where someone can hide) but also are more efficient, meaning they cost less in the long run.

A whole generation of kids is growing up not knowing what a truly dark sky is really about, and that's too bad. It would be a shame if the easiest way for them to see one is when it is faked in a movie scene.

Conclusion