Death from the Skies! (45 page)

One of the best ways to tick off an astronomer—and it can be fun sometimes just to see how he reacts—is to mix up the terms
meteor, meteoroid,
and
meteorite.
The very
best
way to tick off an astronomer is to call him an astrologer.

Pronounced “Cheek-shoo-lube.”

Yes, it
was
the first day of the nineteenth century. Don’t make me lecture you about there not being a year 0.

It’s also illegal. A 1963 test ban treaty (see chapter 4) forbids the detonation of any nuclear weapons in space. However, one would assume that international treaties might be set aside temporarily given the total annihilation of the human species as the alternative.

Technically, it never becomes a liquid; it goes directly from a solid to a gas in a process called
sublimation.

Not to worry, the Sun won’t run out of hydrogen anytime soon—5 million tons sounds like a lot, but it’s only 0.00000000000000000025 percent of the Sun’s mass. We have billions of years of fusion still ahead of us.

You might say that’s a bomb’s distinguishing feature.

You can check this yourself with a simple compass. Find a house lamp or some other appliance connected to a wall outlet. Put the compass near the wire, and turn the appliance on and off. The needle will move, influenced by the temporary magnetic field.

This process, called
convection,
is what causes hot air to rise and cool air to fall, and also can be seen when you heat a pot of water on a stove.

When the Sun is on the horizon, its light passes through more air than when it is overhead, dimming the sunlight considerably and making it easier to see sunspots. At this point, you might be expecting me to exhort you to never ever look at the Sun. However, surprisingly, there has never been a reported case of permanent total blindness caused by looking at the Sun. It
is
possible to damage your eyes looking at the Sun—for example, using cheap sunglasses that dim visible light but not ultraviolet, or looking at the Sun when your pupils have been artificially dilated with drugs—but it’s actually rather difficult to do, and in general the eye heals quickly. I don’t recommend it since damage
is
possible, but it’s unlikely and certainly not worth the hysterics it garners. Having said that, I will point out that looking at the Sun through binoculars or a telescope is in fact
incredibly
dangerous, since they concentrate sunlight. The only 100 percent safe way of looking at the Sun with optical aids without risking boiling the fluids in your eye is to project its image on a piece of paper. There are other, more expensive methods, but this one is easiest. And nothing is more expensive than losing an eye.

This stands for
roentgen equivalent man
where a roentgen is a measure of an amount of radiation. A source may give off a certain number of roentgens of radiation, but the amount that gets absorbed by human tissue is measured in rems.

Going to Mars is even more difficult, since it takes months to travel there. Radiation from flares will be an even bigger priority. Because of its mass, rock makes an inconvenient shield for interplanetary travelers. NASA and other space agencies are busy trying to solve this problem so that trips to Mars can become a reality.

Not all CMEs are associated with flares. Sometimes, they happen all on their own, as more and more field lines get tangled up, resisting the expansion of the matter they constrain. Eventually, the matter breaks free and forms a CME. The magnetic reconnection associated with flares makes it easier to trigger a CME, but it’s not always necessary.

In reality, the magnetic north pole and the geographic north pole don’t coincide; because of the Earth’s ever-changing dynamo the magnetic poles wander, and anyone who needs great accuracy in finding north using a compass needs to correct for that. And things get even worse: what we
call
the Earth’s magnetic north pole is actually, by the way magnetic poles are defined, the
south
magnetic pole. It’s just by tradition that we call it the north pole. And oh—it gets worse still: the poles on a bar magnet are actually labeled for the pole they attract. So the pole labeled “N” on a bar magnet actually tries to point to another magnet’s north pole (it “seeks” the north pole), so the pole labeled “N” is actually the south pole. Confused yet? Yeah, like magnetism isn’t already hard enough to understand.

This is pretty much how a neon sign works; the ionization energy comes from electricity (when the sign is plugged in), and when the electrons recombine with their parent atoms the gas glows. The neon may be mixed with other gases to get different colors.

Oil and natural gas pipelines are conductors too. An electric flow in a pipeline can increase the corrosion rate of the metal, because the voltage change can increase the ability of moist soil to erode the metal. This won’t cause a spectacular collapse like the 1989 power grid failure, but it does reduce the operating lifetime of the pipeline, and can cost billions to retrofit.

Not to be confused with nitrous oxide, N
₂
O, or laughing gas; nitrogen dioxide is far more serious.

If you live in the northern hemisphere, that is. For Australians, New Zealanders, and other upside-down people, reverse these directions.

Even very subtle changes in the shape of the Earth’s orbit can have an effect here, given enough time (like, millennia). Some scientists even speculate that the Sun’s magnetic field protects the Earth from an onslaught of subatomic particles that come from deep space. Called
cosmic rays,
they might seed cloud formation in our air and thus lower the Earth’s temperature. However, the data are
very
marginal for this claim. Much more study is needed to understand these effects. Cosmic rays do have deleterious influences on Earth, which we will see in subsequent chapters, but we can’t include climate change among them just yet.

I’ll note that it’s not even clear that these objects are actually warming at all; the data are sparse. In the case of Jupiter, for example, it’s not a global effect; only small sections of it are warming because of local atmospheric conditions.

Of course, the devil’s in the details. See chapter 7 for an account of what happens to the Sun next.

In reality there are many fusion processes going on, sometimes simultaneously. For example, neon fusion produces the heavier element magnesium and the lighter element oxygen. Then oxygen fusion produces silicon, sulfur, and phosphorus. However, I decided to simplify all this to avoid a profusion of fusion confusion.

The word
disaster
comes from the Latin for “bad star,” so in this case we can be literal.

Just to be clear, there are no stars anywhere near this close capable of blowing up.

That answer shocked me. I had to calculate it twice to make sure I didn’t make some dumb mistake. The Crab is
40 quadrillion miles away,
yet it hurled so much matter outward that 200,000 pounds would hit us even from that distance! Supernovae are immense.

Note the use of the word
only.
Astronomy has a tendency to crush our sense of scale into dust. The mass of the Earth may seem huge to us, but it’s only about a millionth of the mass of the white dwarf.

Really, it’s true. The details aren’t important here, but we’ll cover them in the last chapter. Promise.

To this day that was the largest bomb ever exploded. Theoretically, the same design for the bomb could have been ramped up to give twice that explosive yield, but thankfully it was never tested.

One incident, however, was never clearly defined. In September 1979, what appeared to be a nuclear test well south of the Cape of Good Hope in Africa was detected, but the data were just ambiguous enough that no firm conclusion was ever made. To this day, the origin of this event is unknown.

In fact, it was worse than that. Using timing delays in signal detection actually yields two different positions for a GRB; you need at least one more satellite to distinguish between the two and determine which one is correct. It’s a bit like asking, “What’s the square root of 25?” Both +5 and −5 are correct. And even if you use multiple satellites, the direction to the burst is at best only a very rough estimate.