Journey Through The Solar System, Episode 13 - Uranus, Neptune, Pluto & Beyond
Transcript
00:00NASA's spacecraft have not yet encountered the three outer planets in the solar system,
00:27Uranus, Neptune, and Pluto. Yet these planets are not totally unknown to us.
00:33In recent years, new knowledge has been gained about them.
00:37I'm your host, Larry Ross, Director of Space Programs at NASA's Lewis Research Center in Cleveland, Ohio.
00:43This is our last program in our Journey Through the Solar System series.
00:48In this program, we will examine the three outer planets
00:51and we'll learn about spacecraft messages to other life in the universe.
00:56And we will also look at comets, meteoroids, and asteroids.
01:26Music
01:42There is a zone between Mars and Jupiter known as the asteroid belt.
01:46Here there are thousands of asteroids, many irregular in shape, orbiting the sun.
01:52Most of these small planets vary from as small as a boulder to as large as a mountain.
01:58Some are larger. Ceres is about 600 miles across.
02:03Astronomers think that the Martian moon Phobos may be a captured asteroid.
02:09By examining its photograph closely, scientists may be able to learn more about asteroids.
02:15Music
02:25On a dark night, it is not difficult to see a shooting star, a meteor.
02:29A meteoroid is a chunk of rock or metal orbiting the sun.
02:34Meteoroids may come from the asteroid belt or at one time may have been part of a comet.
02:40When meteoroids enter the Earth's atmosphere,
02:43they often burn as a result of friction between them and the Earth's atmosphere.
02:48Those objects which survive the fiery path to the surface of Earth are called meteoroids.
02:55Sometimes they form craters on impact.
02:58Other times they fall harmlessly to the ground.
03:01Music
03:06Now let's see a short NASA 1980 videotape release about the search for meteorites in Antarctica.
03:12These visitors from outer space come in a variety of shapes, sizes, and colors.
03:18They are meteorites, some 4.5 billion years old.
03:23And they are being found in relatively large numbers in Antarctica.
03:281,300 have been collected during the last few years.
03:32The total number of meteorites in collections around the world was only 2,000 before the Antarctica finds.
03:39So the discoveries there have come as a tremendous surprise
03:43to scientists interested in doing research on these cosmic travelers.
03:47The meteorites are really small fragments from an asteroid belt that might have helped form a planet.
03:53Many of them are drawn into the orbits of Jupiter, Mars, or even the Earth.
03:59So here in Antarctica, preserved by its icy conditions, is some of the oldest material of the solar system.
04:06Some of the very material that went to make up Earth, for example.
04:10Music
04:20By studying meteorites, scientists hope to find answers to two very fundamental questions.
04:25Is there life beyond Earth?
04:28And what are the processes that led to life on Earth?
04:32NASA and the National Science Foundation have been working together to preserve the meteorites for careful analysis.
04:40At the Johnson Space Center's Lunar Receiving Laboratory,
04:43the meteorites are prepared for distribution to scientists all over the world.
04:48They are handled similar to the way samples returned from the Moon by the astronauts are handled.
04:54Music
05:02One of the people analyzing the meteorites is Dr. Cyril Panemperuma,
05:07director of the University of Maryland's Laboratory of Chemical Evolution.
05:11What we are trying to find out in the meteorites is to see whether there are any of these molecules related to life.
05:18There are certain molecules, like the amino acids, which may be described as the building blocks of life.
05:24The meteorites present to us the only prebiotic matter we have laid hands on.
05:30So we like to find out whether in this meteorite, in these samples, are any amino acids, any hydrocarbons.
05:37So the process is one of extracting the meteorite, taking the molecules that are in there,
05:44and dissolving them in a solvent that will get them out.
05:48Then we have a small amount of liquid that will contain some of these molecules.
05:53At that point, we will go to a gas chromatograph, an instrument that will separate these components.
05:59We will inject a very tiny sample into a gas chromatograph
06:04and see whether these individual components can be picked up by a detector.
06:09Dr. Ponamparoma has found organic compounds in the meteorites,
06:14organic compounds which are necessary for all life.
06:17And they are different from any found in living organisms on Earth.
06:21What does that imply is that all those events that led to life may be common in the universe.
06:28So what we said happened on the Earth may be happening somewhere else.
06:35Another member of the solar system family is the comet.
06:39A comet looks like a light bulb with a tail, yet comets give off little of their own light.
06:45Their dust reflects sunlight, thus we can see them.
06:54Like planets, comets orbit the sun.
06:57According to one theory, the nucleus of the average comet is like a dirty iceberg.
07:02The nucleus is made of water, methane, ammonia, carbon dioxide, as well as other materials.
07:09Embedded in this ice are chunks of rock and metal.
07:13Photographs show that the ice ball nucleus is surrounded by a cloud of gas and dust.
07:19The cloud is called the coma.
07:23There is also the tail, which always points away from the sun.
07:28The tail becomes evident when the comet nears the sun.
07:36Scientists have analyzed comet dust, and they think the dust may be four and one half billion years old.
07:45Perhaps comets contain the original stuff from which the solar system was formed.
07:54Some estimates are that there could be a hundred billion comets.
07:58Most of them are theorized to be at least 9.3 trillion miles from the sun.
08:06Sounding rockets, satellites, and observations made aboard the orbiting sky lab
08:11have confirmed the identities of many of the materials in comets.
08:15But comets are difficult to study from long range.
08:19There is no scientific evidence to support the theory.
08:23Scientists are trying to find the origin of comets,
08:26but there is no scientific evidence to support the theory.
08:31But comets are difficult to study from long range,
08:35because many scientists think comets could hold some of the answers to how the solar system was formed.
08:41There have been plans to use spacecraft to closely study comets.
08:49Now we will see a film clip called Comets, Windows into Time.
09:00Comets, Lonely Wanderers of the Night Sky, Drawn to the Sun as a Moth to a Flame.
09:11Comets were born with the sun and the planets four and a half billion years ago.
09:17But unlike the planets, the primitive idea of comets is a myth.
09:23Comets are woven into our history and our legends.
09:27For centuries, they were feared as evil omens, harbingers of ill fortune.
09:33Apprehension and superstition greeted their arrival.
09:37But now they have become a part of our history,
09:41a part of our world, a part of our history,
09:45a part of our world, a part of our world.
09:49Apprehension and superstition greeted their arrival.
09:53But even as some feared these mysterious streaks in the night sky,
09:58others, not affected by superstition,
10:01saw them as part of the natural world that they wanted to understand.
10:06Among them was the English astronomer Edmund Halley.
10:10He not only tracked the great comet of 1682 and calculated its course,
10:15but he was also perceptive enough to realize
10:18that this comet had been observed many times in the past.
10:22He predicted that it would return every 76 years, again and again.
10:30Halley was ridiculed for his prediction,
10:33but the comet's next return proved that he was right.
10:39When this comet, Halley's Comet, returned in 1910,
10:43millions of people were fascinated by its appearance.
10:47This greatest of all comets was intensively studied by scientists
10:52and photographed for the first time.
10:58Our present knowledge about comets is limited to what we have observed from Earth.
11:04We believe that at the heart of a comet is its nucleus,
11:08an irregularly shaped ball of ice and dust.
11:12Surrounding the nucleus is the coma,
11:15a cloud of gas and dust that is boiled off the comet by the sun.
11:21Our knowledge stops at the visible coma.
11:26The coma extends into the tail, the most striking feature of a comet.
11:32The tail develops slowly as the sun's energy reaches out to the approaching comet
11:37and stretches the tail across the sky, sometimes for more than 10 million miles.
11:47Many new comets continue to enter the solar system,
11:51even as old ones disappear.
11:54But from where?
12:01If we were to travel away from the sun,
12:04leaving the planets behind until they fade into the blackness of space,
12:09and until the sun itself is just another bright spot in the sky,
12:14we would see a thin cloud of objects enveloping the entire solar system.
12:20These are the primordial comets,
12:23billions of icy globes no more than 30 miles across.
12:29They have been here unchanged since the beginning of the solar system.
12:40Halley's comet began its first journey around the sun thousands of years ago.
12:48It will come near Earth again in 1986.
12:51In 1972, Dr. Fred L. Ripple suggested that Uranus and Neptune
12:57are big comets.
13:01His theory is that billions of small cometesimals make up those planets.
13:07Ripple, by the way, is the astronomer who in the early 1950s
13:11proposed a model of the average comet,
13:14which seems to fit observations of comets.
13:21But we cannot see Uranus and its five known moons very clearly
13:25from Earth-bound telescopes because of the great distance to them.
13:29Uranus is about 19 times farther from the sun than is Earth.
13:38In this view, we see arrows pointing to three of the five known moons of Uranus.
13:47Uranus is smaller than Jupiter and Saturn,
13:50and is 14 times more massive than Earth.
13:56The NASA Flying Kuiper Observatory was used to discover rings of Uranus.
14:07Below its nine known rings, Uranus is believed to have a deep atmosphere
14:13made mostly of hydrogen and helium.
14:16Methane is present, giving the planet its greenish color.
14:20Scientists believe Uranus has a core of rock and metal
14:24surrounded by ice layers.
14:31To help give us a better picture of Uranus,
14:34the Voyager 2 spacecraft is set to encounter the blue-green planet in 1986.
14:40Judging from the excellent views we received of Jupiter and Saturn,
14:46NASA will make many new discoveries about a planet ground-based observers
14:51have never before seen at close range.
14:58Scientists predict discovery of more Uranus moons.
15:02According to Dr. Dale Crookshank of the University of Hawaii,
15:06the four known moons of Uranus have been discovered.
15:10According to Dr. Dale Crookshank of the University of Hawaii,
15:14the four moons of Uranus that we are able to look at
15:18are made of water, ice, and dust.
15:21Crookshank says astronomers are able to measure
15:24the heat of radiation of the moons.
15:27Those temperatures are colder than that of liquid nitrogen.
15:36The eighth planet from the Sun is Neptune,
15:39which is very much like Uranus.
15:42Neptune is the smallest of the gas giant planets.
15:46Neptune is bluish,
15:48probably due to a variable haze layer in its atmosphere.
15:56Neptune has two known moons,
15:58one of which is shown here by an arrow.
16:03A third known moon may have been discovered in 1981,
16:08but its presence must be confirmed.
16:11The largest of the two moons is Triton,
16:14and it is about in the same range as our moon.
16:18According to Dr. Crookshank,
16:20Triton is covered with patches of methane ice
16:23distributed non-uniformly on the surface.
16:26The atmosphere, he says,
16:28has to be at least a thin methane atmosphere.
16:31Some scientists predict that Triton has locked rotation.
16:35That is, one face of Triton always faces Neptune.
16:39Crookshank wants to find out which face of the moon Triton,
16:43the face towards or away from Neptune, has more methane.
16:47Concentrated observations of the large Neptune moon
16:50scheduled for May of 1983
16:52may provide Crookshank with the answers.
16:59In 1979, pictures taken
17:02through the 16-inch Catalina Observatory telescope
17:05with a charge-coupled device
17:07revealed different regions of Neptune.
17:10High clouds of crystals in the northern and southern hemispheres
17:14produced two bright areas.
17:20At the time the pictures were taken,
17:22the absence of a haze layer in the Neptune region
17:26allowed us to see a deeper layer of methane gas.
17:29The brighter features of the equatorial zone
17:32were seen to move eastward around the planet.
17:38Neptune, which is about the same size as Uranus,
17:41is about 30 times farther from the Sun than is Earth.
17:45In 1989, the Voyager 2
17:48will have its closest encounter with Neptune.
17:52Perhaps then we will confirm
17:54some of our predictions about the planet
17:57as well as answer some questions.
18:03Will we find rings around Neptune?
18:09What will clearer views
18:11of the upper atmosphere of Neptune reveal?
18:15Neptune takes almost 165 Earth years to orbit the Sun.
18:20Nearly twice the time it takes Uranus to circle our home star.
18:24Neptune radiates more heat than it receives from the Sun.
18:28Uranus does not.
18:30This suggests that the core of Neptune is molten rock and iron
18:34with a temperature of about 12,600 degrees Fahrenheit.
18:45Neptune is traditionally known as the eighth planet from the Sun.
18:49Yet since 1979, Neptune has been the most distant planet.
18:53This is because Pluto has a highly elliptical orbit.
18:58Pluto will be within the orbit of Neptune until 1999
19:02when Pluto will once again be the outermost known planet.
19:08Only 17 Earth years of Pluto's 248-year orbit
19:13are spent inside the orbit of Neptune.
19:16At present, there are no plans to send a probe to Pluto.
19:20Of the nine planets, it will be the only one
19:23not visited in this century by an automated spacecraft.
19:31Pluto was discovered in 1930 by photographic means
19:35after a long search for the ninth planet.
19:37The search began after astronomers discovered
19:40that the orbital motions of Neptune
19:42seemed to be affected by a large mass beyond it.
19:46Yet the mass of Pluto was small.
19:49In the 1960s, high-speed computers were used to analyze
19:53orbits of the outer planets
19:55in relation to estimates of the mass of Pluto.
19:59Those estimates of Pluto's mass fell from roughly
20:02a fifth of the mass to a tenth of the mass of Earth.
20:07Then in 1978, U.S. naval astronomer James Christie
20:11declared that he had discovered a moon closely orbiting Pluto.
20:15The moon was named Charon
20:17and was estimated to be as much as a quarter of Pluto's mass.
20:21Based on observations of the new moon,
20:24estimates of Pluto's mass went down to 1 500th that of Earth.
20:29The mass of Pluto is important
20:31because if it is as small as calculated,
20:34something else must affect the orbits of Uranus and Neptune.
20:41One theory is that a tenth planet
20:43exists somewhere beyond Pluto's orbit.
20:53Some astronomers speculate a dark star
20:55as many as 50 billion miles from Pluto
20:58could affect the outer planet orbits.
21:01Another possibility is that a black hole
21:04could be 100 billion miles past Neptune's orbit
21:07and the black hole could affect the orbits of the outer planets.
21:13A black hole is believed to be the final stage
21:16of a collapsed massive star.
21:18The material of the collapsed star is so densely packed
21:22and the force of its gravity is so great
21:25that even light cannot escape its pull.
21:32Pioneer 10
21:38The Pioneer spacecraft,
21:40which first surveyed Jupiter and Saturn at close range,
21:43are now the two man-made objects most distant from Earth.
21:47By July 1983, Pioneer 10 will be beyond the nine known planets.
21:53Pioneer 11 is nearly as far out as Pioneer 10,
21:57but at the other side of the solar system.
22:02Scientists think that the two Pioneer spacecraft
22:06will be able to help predict the distance and size of an object
22:10which could affect the orbits of the outer planets.
22:16It is thought that a massive body,
22:18which is a relatively long distance from the outer planets,
22:21would exert about the same gravity force on both Pioneer probes,
22:25even though they are at opposite sides of the solar system.
22:29On the other hand, a smaller body, closer to the outer planets,
22:33might only affect one of the Pioneer spacecraft.
22:51Man is just beginning to study the boundaries of the solar system.
22:55To delve into the unknown, man must use spacecraft.
23:02In the next few years,
23:04if the Voyager 2 spacecraft missions to Uranus and Neptune go well,
23:08some of the theories presented here will be replaced with fact and new questions.
23:18Meanwhile, the Pioneer 10 and 11 spacecraft continue to sail the cosmos
23:23into what could be eternity in human terms.
23:31Each of these probes carry with it a message
23:34to other possible residents of the universe.
23:37The message is designed to show intelligent beings elsewhere
23:40the origin of the spacecraft.
23:43The communication is etched into a gold anodized aluminum plate,
23:47six by nine inches,
23:49and it is attached to antenna support struts.
23:53The lines radiating from a common point
23:56show our sun's position relative to the 14 pulsars.
24:00The one dash symbols are binary numbers
24:04showing the frequencies of the pulsars relative to the hydrogen atom.
24:11A symbol of the hydrogen atom is in the upper left-hand corner.
24:24Near the bottom of the message, the solar system is represented,
24:29and Earth, the third planet, is seen as the origin of the Pioneer probe.
24:46Perhaps never, or perhaps millions of years from now,
24:50intelligent beings will rendezvous with Pioneer in space
24:53and decipher its message.
25:00Will they be able to appreciate or comprehend
25:03the outlines of the beings, man and woman,
25:06etched into the plate?
25:13The two Voyager craft carry with them
25:16even more sophisticated messages for extraterrestrials
25:19who might intercept the craft millions of years in the future
25:23in some remote part of the Milky Way.
25:32Encoded on a disc, much like a phonograph record,
25:35are sights and sounds selected from around the world.
25:50This ends our series of 13 programs called
25:53Journey Through the Solar System.
25:58Now let's see some of the sights and sounds of our world
26:01being sent to the far reaches of space.
26:04We step out of our solar system into the universe,
26:07seeking only peace and tranquility.
26:10We are the first of a series of programs
26:13called Journey Through the Solar System.
26:16Into the universe, seeking only peace and friendship,
26:19to teach if we are called upon,
26:22to be taught if we are fortunate.
26:25Journey Through the Solar System
26:43Our fantastic journey is not at an end.
26:50Mankind will continue to explore and learn.
26:55We have just begun.