Transcript[]
Text reads: The Mysteries of Life with Tim and Moby
Moby is in his backyard at night, looking at the night sky with a handheld telescope.
MOBY: Beep.
Tim stands next to Moby. Tim is holding a sheet of paper.
TIM: Uh, you can't see Mercury at this time of night; Moby.
Tim reads from a typed letter.
TIM: Dear Tim and Moby, what planet is closest to the sun? Love, Rexi342. Mercury is the second planet closest to the sun and the smallest planet in our solar system between the Sun and Venus.
An animation shows the sun and the planets of our solar system. Mercury is closest to the sun.
TIM: Actually, since it's so close to the sun, most people can only see it at dawn, just before the sun rises, at dusk, just after the sun sets, or during a solar eclipse.
An animation shows Mercury near the horizon among the stars in a darkening sky.
TIM: Mercury's being so close to the sun also means that it switches back and forth between being extremely hot and extremely cold. During the daytime, temperatures on the equator can reach 430 degrees Celsius. That's hot enough to melt lead.
An animation shows the surface of Mercury in the daytime. A thermometer reads: 430 degrees Celsius, before bursting and melting into a puddle.
TIM: And at night, especially inside craters at the poles, temperatures can go down to −180 degrees Celsius.
An animation shows the craters Tim describes. As night falls, a thermometer reads a lower and lower temperature until it reaches −180 degrees Celsius.
TIM: It only takes 88 Earth days for Mercury to orbit the sun.
An animation shows Mercury orbiting the sun.
TIM: But it rotates really slowly, about once every 59 Earth days. Which means that its day is almost as long as its year.
An animation shows Mercury's rotation. The planet looks dark and cold, and it rotates very slowly.
TIM: A cool thing happens because Mercury rotates so slowly and orbits so fast. Sometimes the sun moves backwards.
MOBY: Beep.
TIM: Well, Mercury's orbit is really unusual. It moves from being very close to the sun to being much farther away.
An animation of Mercury and the sun illustrates the orbit Tim describes.
TIM: By the time Mercury rotates once on its axis, it's already completed two-thirds of its orbit around the sun. Compare that to Earth. In one day here, we've only completed a small fraction of our orbit.
Two animations compare Mercury's rotation to that of Earth. Earth rotates rapidly compared to Mercury, but its orbit around the sun takes longer.
TIM: On Earth, the rotation of the planet makes the sun appear to move across the sky.
An animation shows Tim standing in a wilderness. He watches the sun rise from behind a mountain as a bird circles overhead.
TIM: On Mercury, the sun's path across the sky is influenced by both the rotation and the revolution. That makes the sun's path there kind of weird.
An animation shows Moby standing on Mercury. The sun looks like it is swinging back and forth across the sky.
MOBY: Beep.
TIM: Oh, Mercury doesn't have any satellites, and it's only a little bigger than Earth's moon.
An image compares the size of Mercury to the size of the moon. Text indicates that the moon is 3,479 kilometers in diameter. Additional text indicates that Mercury is 4,878 kilometers in diameter.
TIM: In 1974, Mariner 10 showed that the exterior of Mercury looks a lot like our own moon, actually.
An animation shows the space probe Mariner 10 flying slowly past the planet Mercury.
TIM: It's barren and cratered.
An image shows Mariner 10 from the empty, cratered surface of Mercury.
MOBY: Beep.
TIM: The information we got from Mariner 10 was surpassed by the images we received from a craft called MESSENGER, which entered Mercury's orbit in March 2011.
An animation shows the MESSENGER spacecraft moving slowly through of space.
TIM: It showed that Mercury's surface isn't just pocked with craters. There are smooth volcanic plains as well.
MOBY: Beep.
TIM: Yeah, the inside of Mercury is a little like the earth's inside. It has an iron core and a rocky mantle, and a thin crust. The iron core gives it a magnetic field, but it's only about one-hundredth as strong as Earth's.
An animation shows a cross-section of Mercury. Graphics indicate the parts of the planet that Tim describes. Animated lines show the range and location of Mercury's magnetic field.
MOBY: Beep.
Moby looks through his handheld telescope and points at the sky.
TIM: No. That's not Mercury, either.
MOBY: Beep.
Moby frowns. Tim sighs.
TIM: Fine! It's Mercury.