WEBVTT - How Does Planet Mercury Work?

0:00:01.920 --> 0:00:06.480
<v Speaker 1>Welcome to brain Stuff production of I Heart Radio. Hey

0:00:06.519 --> 0:00:10.560
<v Speaker 1>brain Stuff, Lauren Bogelbaum. Here. You'd like to think you

0:00:10.640 --> 0:00:13.600
<v Speaker 1>know your neighbors, but sometimes they'll catch you off guard.

0:00:14.520 --> 0:00:17.840
<v Speaker 1>That diminutive world called Mercury is the first planet from

0:00:17.840 --> 0:00:20.919
<v Speaker 1>our Sun, Venus's second, Earth is the third, and dear

0:00:20.920 --> 0:00:25.119
<v Speaker 1>old Mars is number four common knowledge, but that numbering

0:00:25.280 --> 0:00:28.720
<v Speaker 1>obscures certain truths. With its tight orbit around the Sun,

0:00:28.960 --> 0:00:32.000
<v Speaker 1>Mercury can't ventures far away from Earth as Venus and

0:00:32.040 --> 0:00:36.040
<v Speaker 1>Mars can during their larger orbits, so most of the time,

0:00:36.400 --> 0:00:40.000
<v Speaker 1>Mercury is closer to Earth than any other planet, despite

0:00:40.040 --> 0:00:43.239
<v Speaker 1>its place in the planetary lineup. And that's far from

0:00:43.240 --> 0:00:47.120
<v Speaker 1>the weirdest thing about Mercury's travel patterns. Of all the

0:00:47.120 --> 0:00:49.879
<v Speaker 1>planets in the Solar System, Mercury orbits our Sun at

0:00:49.880 --> 0:00:52.960
<v Speaker 1>the fastest rate. It zips around our star with an

0:00:52.960 --> 0:00:55.520
<v Speaker 1>average speed of around one hundred and five thousand, nine

0:00:55.600 --> 0:00:58.640
<v Speaker 1>hundred miles per hour or a hundred and seventy thousand,

0:00:58.640 --> 0:01:02.160
<v Speaker 1>five hundred kilometers per hour. The planet's namesake was a

0:01:02.200 --> 0:01:05.880
<v Speaker 1>real speedster too. In Roman mythology, Mercury was the fleet

0:01:05.880 --> 0:01:10.240
<v Speaker 1>footed god of commerce and communication, among other things. Recognizable

0:01:10.240 --> 0:01:14.039
<v Speaker 1>by his winged sandals. Earth takes a little more than

0:01:14.080 --> 0:01:16.559
<v Speaker 1>three hundred and sixty five days to loop around the sun.

0:01:17.240 --> 0:01:19.720
<v Speaker 1>Mercury does the same thing in a fraction of the time.

0:01:20.360 --> 0:01:23.440
<v Speaker 1>One Mercury in year is equal to a brisk eighty

0:01:23.480 --> 0:01:27.960
<v Speaker 1>eight earth days vacationing there would be a disorienting experience

0:01:29.000 --> 0:01:31.679
<v Speaker 1>on Mercury. The years may be quick, but the days

0:01:31.720 --> 0:01:35.399
<v Speaker 1>are very long. The planet finishes a new rotation around

0:01:35.440 --> 0:01:38.920
<v Speaker 1>its own axis once every fifty nine earth days, which

0:01:38.959 --> 0:01:42.200
<v Speaker 1>means that every day on Mercury takes up almost exactly

0:01:42.319 --> 0:01:46.800
<v Speaker 1>two thirds of every year. But due to some further strangeness,

0:01:46.840 --> 0:01:50.520
<v Speaker 1>each day on Mercury isn't guaranteed to have a sunrise

0:01:50.560 --> 0:01:54.240
<v Speaker 1>and a sunset. If we define a day not as

0:01:54.280 --> 0:01:57.080
<v Speaker 1>a complete rotation of a planet around its axis, but

0:01:57.240 --> 0:02:00.720
<v Speaker 1>rather as a solar day, a one complete day night cycle,

0:02:01.120 --> 0:02:03.120
<v Speaker 1>the amount of time it takes our son to return

0:02:03.200 --> 0:02:06.200
<v Speaker 1>to a specific point in the sky, then a single

0:02:06.360 --> 0:02:09.480
<v Speaker 1>day on Mercury is a hundred and seventy six earth

0:02:09.560 --> 0:02:13.320
<v Speaker 1>days long. That's the rough equivalent of two full Mercury

0:02:13.400 --> 0:02:17.200
<v Speaker 1>in years. That's because Mercury's orbit is what we refer

0:02:17.320 --> 0:02:21.840
<v Speaker 1>to as eccentric. No, not eccentric like Willy Wonka is eccentric.

0:02:22.240 --> 0:02:25.560
<v Speaker 1>Eccentricity is a term astronomers used to describe the shape

0:02:25.600 --> 0:02:29.120
<v Speaker 1>of a planet or moon's orbit. No planet orbits its

0:02:29.160 --> 0:02:31.880
<v Speaker 1>star in a perfect circle. The extent to which had

0:02:31.919 --> 0:02:36.240
<v Speaker 1>given orbit deviates from being circular is cold. It's eccentricity.

0:02:36.880 --> 0:02:39.720
<v Speaker 1>If an orbit was one circular, would say it had

0:02:39.760 --> 0:02:43.440
<v Speaker 1>an eccentricity of zero. Let The records show that Earth's

0:02:43.520 --> 0:02:48.239
<v Speaker 1>orbit boasts an eccentricity of just zero point zero one seven,

0:02:48.919 --> 0:02:53.760
<v Speaker 1>so it's almost a circle, but not quite. Mercury's orbit

0:02:53.800 --> 0:02:57.640
<v Speaker 1>looks more squashed or elliptical. By comparison of all the

0:02:57.680 --> 0:03:01.040
<v Speaker 1>planets in our beloved Solar system, Cury has the most

0:03:01.080 --> 0:03:04.560
<v Speaker 1>eccentric orbit. The amount of space between this world and

0:03:04.600 --> 0:03:07.760
<v Speaker 1>our Sun ranges from just twenty nine million miles to

0:03:07.880 --> 0:03:10.639
<v Speaker 1>thirty six million miles during the course of its elliptical

0:03:10.639 --> 0:03:13.520
<v Speaker 1>trip around the Sun. That's a forty six million to

0:03:13.639 --> 0:03:19.080
<v Speaker 1>fifty eight million kilometers. Consequently, Mercury's travel speed increases as

0:03:19.120 --> 0:03:22.120
<v Speaker 1>it gets closer to the star. Those changes in speed

0:03:22.160 --> 0:03:24.880
<v Speaker 1>and distance from the Sun account for the strange solar days.

0:03:25.520 --> 0:03:27.919
<v Speaker 1>When you view the Sun from some places on Mercury,

0:03:28.200 --> 0:03:30.720
<v Speaker 1>it appears to freeze in place part way through its

0:03:30.760 --> 0:03:34.560
<v Speaker 1>journey across the sky, then move backwards before going forward

0:03:34.560 --> 0:03:37.960
<v Speaker 1>again in its route to the opposite horizon. Depending on

0:03:38.000 --> 0:03:40.280
<v Speaker 1>where you are on the planet, this might mean that

0:03:40.320 --> 0:03:42.760
<v Speaker 1>you get to sunrises in a row as the Sun

0:03:42.840 --> 0:03:46.360
<v Speaker 1>dips back below the skyline before fully rising, or two

0:03:46.400 --> 0:03:48.960
<v Speaker 1>sunsets in a row as it pops back up before

0:03:49.000 --> 0:03:53.040
<v Speaker 1>fully setting, And of course all of this reeks havoc

0:03:53.120 --> 0:03:56.440
<v Speaker 1>on the planet's temperatures on Mercury, they can range as

0:03:56.520 --> 0:03:59.840
<v Speaker 1>high as eight hundred degrees fahrenheit that's four thirty celsius,

0:04:00.160 --> 0:04:03.120
<v Speaker 1>or as low as negative two nine degrees fahrenheit or

0:04:03.200 --> 0:04:06.760
<v Speaker 1>negative one eight celsius. As you could expect, the side

0:04:06.800 --> 0:04:08.840
<v Speaker 1>of the planet that's facing the Sun at any time

0:04:08.960 --> 0:04:12.880
<v Speaker 1>will be a good deal hotter, and on hot days

0:04:13.120 --> 0:04:17.680
<v Speaker 1>we could all use some ice in NASA's Messenger spacecraft

0:04:17.720 --> 0:04:21.240
<v Speaker 1>observed deposits of frozen water on Mercury. The ice was

0:04:21.240 --> 0:04:24.239
<v Speaker 1>found at the bottoms of deep craters around the northern pole,

0:04:24.520 --> 0:04:26.840
<v Speaker 1>which are protected from the sun all year long due

0:04:26.839 --> 0:04:29.720
<v Speaker 1>to Mercury's lack of tilt around its axis of rotation.

0:04:30.320 --> 0:04:33.279
<v Speaker 1>Earth tilts twenty three point five degrees on its axis,

0:04:33.320 --> 0:04:35.840
<v Speaker 1>giving us seasons and exposing the poles to the Sun.

0:04:36.400 --> 0:04:40.000
<v Speaker 1>But Mercury only tilts two degrees, meaning it spins almost

0:04:40.000 --> 0:04:44.000
<v Speaker 1>completely upright, protecting its poles and preventing seasons from occurring.

0:04:45.160 --> 0:04:49.719
<v Speaker 1>But back to that ice. Paradoxically, Mercury's hottest temperatures could

0:04:49.720 --> 0:04:52.159
<v Speaker 1>be responsible for some of the ice that it possesses.

0:04:52.920 --> 0:04:56.640
<v Speaker 1>Our Sun is constantly releasing charged protons and electrons in

0:04:56.760 --> 0:05:00.640
<v Speaker 1>streams known as solar winds. Earth is shielded by a

0:05:00.640 --> 0:05:04.880
<v Speaker 1>powerful magnetic field, which deflects many of these. Mercury has

0:05:04.880 --> 0:05:07.240
<v Speaker 1>had a magnetic field of its own four around three

0:05:07.240 --> 0:05:11.279
<v Speaker 1>point nine billion years. However, it's significantly weaker than the

0:05:11.279 --> 0:05:14.440
<v Speaker 1>one we enjoy here on Earth. If a recent scientific

0:05:14.480 --> 0:05:17.600
<v Speaker 1>model is correct, The intense heat of the planet's sun

0:05:17.640 --> 0:05:21.960
<v Speaker 1>facing side triggers chemical reactions between solar wind particles and

0:05:22.040 --> 0:05:25.719
<v Speaker 1>minerals buried in the soil. These are thought to create

0:05:25.800 --> 0:05:30.839
<v Speaker 1>traveling water molecules that later become ice. Of all the

0:05:30.880 --> 0:05:33.560
<v Speaker 1>frozen water on Mercury may have been generated this way,

0:05:35.440 --> 0:05:38.560
<v Speaker 1>Mercury doesn't have any moons to call its own. As

0:05:38.600 --> 0:05:40.960
<v Speaker 1>a matter of fact, With a diameter of just three thousand,

0:05:41.000 --> 0:05:45.480
<v Speaker 1>thirty miles or four thousand kilometers, Mercury isn't much bigger

0:05:45.520 --> 0:05:49.920
<v Speaker 1>than Earth's Moon easily. Mercury is the smallest planet in

0:05:49.960 --> 0:05:53.560
<v Speaker 1>our Sun's orbit, yet evidence tells us that it used

0:05:53.560 --> 0:05:57.080
<v Speaker 1>to be larger. Mercury is interesting to look at from

0:05:57.080 --> 0:06:00.680
<v Speaker 1>a topographic standpoint. The thin atmosphere for his very little

0:06:00.720 --> 0:06:05.120
<v Speaker 1>protection from asteroids, so impact craters are abundant. A single

0:06:05.160 --> 0:06:07.640
<v Speaker 1>photo taken by the Messenger Probe in two thousand eight

0:06:07.839 --> 0:06:11.440
<v Speaker 1>shows seven hundred and sixty three identifiable craters within a

0:06:11.520 --> 0:06:13.680
<v Speaker 1>region of the planet's surface just a hundred and seventy

0:06:13.680 --> 0:06:16.600
<v Speaker 1>two miles wide. That's two hundred and seventy six kilometers.

0:06:17.839 --> 0:06:20.720
<v Speaker 1>It's traditional to name these craters after writers, given that

0:06:20.880 --> 0:06:24.440
<v Speaker 1>eloquence is one of the realms of the mythological god Mercury.

0:06:24.600 --> 0:06:28.559
<v Speaker 1>Truman Capote, Batteline la Engel, Betty Alver, and John Lennon

0:06:28.680 --> 0:06:31.640
<v Speaker 1>are just some of the visionaries with their own namesake craters.

0:06:33.080 --> 0:06:36.480
<v Speaker 1>The planet's face is also marked by fault scarps. These

0:06:36.520 --> 0:06:39.040
<v Speaker 1>are cliff ridges that were first sighted on Mercury in

0:06:39.040 --> 0:06:42.040
<v Speaker 1>the nineteen seventies. Some of the smaller ones appeared to

0:06:42.080 --> 0:06:45.520
<v Speaker 1>be around just fifty million years old, making them geologically

0:06:45.640 --> 0:06:50.000
<v Speaker 1>pretty young. Mercury itself formed around four point five billion

0:06:50.080 --> 0:06:53.520
<v Speaker 1>years ago. Since then, its metallic core has been cooling

0:06:53.600 --> 0:06:56.880
<v Speaker 1>down at a rapid pace, and as a result, the

0:06:56.960 --> 0:07:01.120
<v Speaker 1>whole planet is currently shrinking. The diameter of mercury may

0:07:01.160 --> 0:07:03.000
<v Speaker 1>have contracted by as much as eight and a half

0:07:03.080 --> 0:07:06.560
<v Speaker 1>miles or fourteen kilometers over the eons. This has had

0:07:06.600 --> 0:07:10.160
<v Speaker 1>a tremendous effect on the planet's rocky outer surface. Those

0:07:10.280 --> 0:07:13.880
<v Speaker 1>previously mentioned fault scarps are born when crust materials break

0:07:13.960 --> 0:07:17.320
<v Speaker 1>apart and press into each other, forcing some terrain upward.

0:07:18.320 --> 0:07:22.400
<v Speaker 1>And because it's tectonically active in its own peculiar way, Mercury,

0:07:22.760 --> 0:07:27.680
<v Speaker 1>like Earth, may experience surface level earthquakes. Mercury quakes will

0:07:27.680 --> 0:07:30.520
<v Speaker 1>definitely be a topic worth investigating as we plot out

0:07:30.560 --> 0:07:38.960
<v Speaker 1>future pro missions to our curious little neighbor. Today's episode

0:07:39.000 --> 0:07:41.720
<v Speaker 1>was written by Mark Mancini and produced by Tyler clang Or.

0:07:41.800 --> 0:07:43.800
<v Speaker 1>More on this and lots of other curious topics, visit

0:07:43.840 --> 0:07:46.400
<v Speaker 1>how stuff works dot com. Brain Stuff is production of

0:07:46.440 --> 0:07:49.200
<v Speaker 1>Iyheart Radio. Or more podcasts my heart Radio, visit the

0:07:49.240 --> 0:07:52.000
<v Speaker 1>iHeart Radio app. Apple podcasts, or wherever you listen to

0:07:52.080 --> 0:07:52.840
<v Speaker 1>your favorite shows.