as vacuum
weightlessness in
spaghettification
spectrum
Spica
Spörer, Gustav
Starfish Prime
starquakes
stars
binary systems of
birth of
blue
brightness of
collisions of
core collapse in
definition of
destruction and death of
distance between
dust created by
elements in cores of
expansion of
explosions of
gravity of
guest
helium in
hydrogen in
life of
life transported to
magnetic fields of
mass of
in Milky Way Galaxy
neutron
nuclear fusion of
orbiting in galaxies
oscillation of
polarized light from
population of
red
red dwarfs
red giants
red supergiants
runaway
sending probes to
shooting
sizes of
spinning
in Stelliferous Era
Sun
temperatures of
variable
white dwarfs
Star Trek
stellar mass black holes
stellar wind
Stelliferous Era
stratosphere
Strong, Ian
subatomic particles
subgiants
sublimation
Sun:
age of
aging of
asteroids orbiting
birth of
brightening of
color of
death as inevitable for
death of (what if?)
degeneracy of
Sun (cont.)
Earth’s climate affected by
energy emitted by
expansion of
gamma rays emitted by
and gravity
helium on
on the horizon
hydrogen on
looking at
luminosity of
magnetic field of
magnetism on
mass of
in “Milkomeda” collision
in Milky Way
and nuclear fusion
orbit of
oscillation of
planets orbiting
power of
pressure building in
radiation emitted from
as red giant
size of
solar flares
spinning on axis
in spiral arm
as star
as subgiant
temperature of
ultraviolet output of
visible light from
what if?
as white dwarf
sunspot cycle
sunspots
and climate change
faculae of
and magnetism
on March
minimum
pressure in
what if?
Super-Kamiokande observatory, Japan
supermassive black holes (SMBHs)
supernovae:
brightness of
Crab Nebula
dust created by
and Earth’s ozone layer
effects of
energy released in
explosions of
light flowing from
possibility of
in
Type and Type
what if?
Swift satellite
Tadpole galaxy
Tau Ceti
Taurus, new star of
telescopes, as time machines
terminal velocity
terraforming
Tertiary period
test ban treaty ()
theory, use of term
thermonuclear bombs
Orionis
tidal force
tidal streams
time:
beginning of
deep
dilation of
telescopes as time machines
Titan transformers transverse velocity trilobites tsunamis:
caused by asteroid shock wave
caused by earthquakes
December
Tufnel, Nigel
tunneling event
Mathilde
UFO sightings
ultraviolet (UV)
understanding, as goal
Universe:
acceleration of
age of
aging of
before beginning of
beginning of
behavior of
Black Hole Era
changing laws of
Cosmic Epochs of
Dark Era
death, possibility of
Degenerate Era
early period of
ekpyrotic
expansion of
future extrapolated for
Grand Unification Epoch
horizon of
infinity of
Primordial Era
rebirth of
Stelliferous Era
tunneling event in
uranium:
fission of
half-life of
radioactivity of
Uranus
vacuum
variable stars
Vela satellites
Venus
early condition of
movement of
and Sun as red giant
Virgo
Virgo Cluster
viruses
as precursors of life
structural simplicity of
visible light
volcanic activity, effects of
weightlessness
Wells, H. G.
white dwarfs
collision between
and dying Universe
formation of
Sun as
WR
X-rays
atmospheric absorption of
direct exposure to
emitted by SMBHs
Yucatán Peninsula, Mexico, asteroid impact near
1
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.
2
Pronounced “Cheek-shoo-lube.”
3
Yes, it was the first day of the nineteenth century. Don’t make me lecture you about there not being a year 0.
4
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.
5
Technically, it never becomes a liquid; it goes directly from a solid to a gas in a process called sublimation.
6
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.
7
You might say that’s a bomb’s distinguishing feature.
8
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.
9
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.
10
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.
11
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.
12
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.
13
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.
14
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.
15
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.
16
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.
17
Not to be confused with nitrous oxide, N2O, or laughing gas; nitrogen dioxide is far more serious.
18
If you live in the northern hemisphere, that is. For Australians, New Zealanders, and other upside-down people, reverse these directions.
19
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.
20
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.
21
Of course, the devil’s in the details. See chapter 7 for an account of what happens to the Sun next.
22
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.
23
The word disaster comes from the Latin for “bad star,” so in this case we can be literal.
24
Just to be clear, there are no stars anywhere near this close capable of blowing up.
25
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.
26
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.
27
Really, it’s true. The details aren’t important here, but we’ll cover them in the last chapter. Promise.
28
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.
29
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.
30
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.
31
A spectrum is what you get when you run light through a prism or a finely etched grating. The light is separated into its individual colors, like a rainbow. When measured very carefully, a wealth of information can be obtained about the source of the light, including its temperature, chemical composition, and for some objects, like galaxies and GRBs, even their distance.
32
Stretch your brain back to dim memories of high school math: the area of a sphere = 4πr 2.
33
Pronounced “ATE a CARE in Ay,” for those practicing at home.
34
Actually, Eta may be a binary star, two stars orbiting each other. There is so much glare and interference from all the material surrounding the star that astronomers still aren’t 100 percent sure.
35
These findings are still controversial. This is a new field of science, and the models are somewhat shaky. Still, if you take away anything, just remember that a nearby gamma-ray burst is bad.
36
Get used to that. Your common sense is going to take a beating here.
37
This means that astronauts orbiting the Earth are not weightless because they are beyond Earth’s gravity; they feel weightless because they’re falling. When you are sitting in a chair, you feel gravity as pulling you down into the seat, which supports your weight. If there is nothing to support your weight, you don’t feel the force of gravity, so when you’re falling you feel weightless. This is why astronauts appear weightless in orbit (described as “free fall”). At the usual orbital height (300 miles or so) the Earth’s gravity is only about 10 percent weaker than it is on the surface. Think of it this way: if the Earth’s gravity weren’t pulling on the astronauts, they would go flying off into deep space!
38
That distance is about 700 million miles from the Earth, so you’ll be thrusting a long time: well over a thousand years. Better pack a lunch.
39
More specifically, nonrotating black holes are spherical. In reality, most black holes are created from rotating stars, and that rotation is amplified when the core of a star collapses into a black hole. Like any rapidly rotating object, black holes can bulge out at their equators from centripetal acceleration.
40
The event horizon is not the physical surface of a black hole. A black hole doesn’t really have a surface; as far as we can tell, the matter in the black hole has shrunk all the way down to a mathematical point with literally zero size, called the singularity. The event horizon is the point where, at some distance from the singularity, the escape velocity equals the speed of light. The matter forming the black hole basically has no size, while the event horizon can be many miles across. Like I said, black holes are weird.
41
The corollary to this is: if you want to age less, move around really quickly all the time so others see your clock as running more slowly. Or you can sit around reading books on black holes and other astronomical dangers, and others will see your clock as running just like theirs.
42
Just to be clear, mass and weight are different. Mass is a property of matter; you can think of it as how much matter there is, and we measure it in grams or kilograms. Weight is the force of gravity on that mass, and we measure it in pounds. A cannonball has the same mass whether it’s on the Earth or the Moon, but on the Moon it weighs one-sixth as much because gravity is one-sixth as strong; on the Earth 1 kilogram weighs 2.2 pounds, but on the Moon it weighs about 0.36 pound.
43
Actually, because of the physics of solid bodies, the truth is that the mass above you doesn’t pull on you at all, oddly enough. Newton was the first person to be able to work that out mathematically. Basically, once you are inside an object like the Sun, the only mass you need to worry about is from the stuff between you and the center.
Death From the Skies!: These Are the Ways the World Will End... Page 32