the solar system the solar system consists of the sun and those celestial objects bound to it by...

The Solar SystemThe Solar System

The Solar SystemThe Solar System

The Solar System consists of the The Solar System consists of the SunSun and and those those celestial objectscelestial objects bound to it by bound to it by gravitygravity. These objects are the eight . These objects are the eight planetsplanets, their 166 known , their 166 known moonsmoons, five , five dwarf planetsdwarf planets, and billions of , and billions of small bodiessmall bodies. . The small bodies include The small bodies include asteroidsasteroids, , icyicy KuiperKuiper belt belt objects, objects, cometscomets, , meteoroidsmeteoroids, , and and interplanetary dustinterplanetary dust..

What is a planet? What is a planet?

A planet is a celestial body that (a) is in A planet is a celestial body that (a) is in orbit around the Sun, (b) has sufficient orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid mass for its self-gravity to overcome rigid body forces so that it assumes a body forces so that it assumes a hydrostatic equilibrium (nearly round) hydrostatic equilibrium (nearly round) shape and (c) has cleared the shape and (c) has cleared the neighborhood around its orbit.neighborhood around its orbit.

The SunThe Sun

The SunThe Sun The Sun is the closest star to The Sun is the closest star to EarthEarth, at a mean distance , at a mean distance

from our planet of 149.60 million kilometers (92.96 from our planet of 149.60 million kilometers (92.96 million miles). This distance is known as an astronomical million miles). This distance is known as an astronomical unit (abbreviated AU), and sets the scale for measuring unit (abbreviated AU), and sets the scale for measuring distances all across the solar system. The Sun, a huge distances all across the solar system. The Sun, a huge sphere of mostly ionized gas, supports life on Earth. It sphere of mostly ionized gas, supports life on Earth. It powers photosynthesis in green plants, and is ultimately powers photosynthesis in green plants, and is ultimately the source of all food and fossil fuel. The connection and the source of all food and fossil fuel. The connection and interactions between the Sun and Earth drive the interactions between the Sun and Earth drive the seasons, ocean currents, weather, and climate.seasons, ocean currents, weather, and climate.

The SunThe Sun

Distance from Earth: 149,597,900 kmDistance from Earth: 149,597,900 kmVolume: 1,412,200,000,000,000,000 km3Volume: 1,412,200,000,000,000,000 km3Mass: 1,989,000,000,000,000,000,000,Mass: 1,989,000,000,000,000,000,000,

000,000,000 kg000,000,000 kg

MercuryMercury

MercuryMercury Mercury's elliptical orbit takes the small planet as close Mercury's elliptical orbit takes the small planet as close

as 47 million kilometers and as far as 70 million as 47 million kilometers and as far as 70 million kilometers from the kilometers from the SunSun. If one could stand on the . If one could stand on the scorching surface of Mercury when it is at its closest scorching surface of Mercury when it is at its closest approach, the Sun would appear almost three times as approach, the Sun would appear almost three times as large as it does when viewed from Earth. Temperatures large as it does when viewed from Earth. Temperatures on Mercury's surface can reach 430 degrees Celsius .on Mercury's surface can reach 430 degrees Celsius .

Because Mercury is so close to the Sun, it is hard to Because Mercury is so close to the Sun, it is hard to directly observe from directly observe from EarthEarth, except during twilight. , except during twilight.

MercuryMercury

Distance from the Sun: 57,909,175 kmDistance from the Sun: 57,909,175 kmVolume: 60,827,200,000 km3Volume: 60,827,200,000 km3Mass: 330,220,000,000,000,000,000,000 Mass: 330,220,000,000,000,000,000,000

kgkg

VenusVenus

VenusVenus At first glance, if At first glance, if EarthEarth had a twin, it would be had a twin, it would be

Venus. The two planets are similar in size, Venus. The two planets are similar in size, mass, composition, and distance from the mass, composition, and distance from the SunSun. .

Venus has no ocean. Venus is covered by thick, Venus has no ocean. Venus is covered by thick, rapidly spinning clouds that trap surface heat, rapidly spinning clouds that trap surface heat, creating a scorched greenhouse-like world with creating a scorched greenhouse-like world with temperatures hot enough to melt lead and temperatures hot enough to melt lead and pressure so intense that standing on Venus pressure so intense that standing on Venus would feel like the pressure felt 900 meters deep would feel like the pressure felt 900 meters deep in Earth's oceans. in Earth's oceans.

VenusVenus

Distance from the Sun: 108,208,930 kmDistance from the Sun: 108,208,930 kmVolume: 928,400,000,000 km3Volume: 928,400,000,000 km3Mass: 4,868,500,000,000,000,000,000,Mass: 4,868,500,000,000,000,000,000,

000 kg000 kg

EarthEarth

EarthEarth

Earth, our home planet, is the only planet in our Earth, our home planet, is the only planet in our solar system known to harbor life. All of the solar system known to harbor life. All of the things we need to survive are provided under a things we need to survive are provided under a thin layer of atmosphere that separates us from thin layer of atmosphere that separates us from the uninhabitable void of space. Earth is made the uninhabitable void of space. Earth is made up of complex, interactive systems that are often up of complex, interactive systems that are often unpredictable. Air, water, land, and life - unpredictable. Air, water, land, and life - including humans - combine forces to create a including humans - combine forces to create a constantly changing world that we are striving to constantly changing world that we are striving to understand. understand.

EarthEarth Viewing Earth from the unique perspective of space Viewing Earth from the unique perspective of space

provides the opportunity to see Earth as a whole. provides the opportunity to see Earth as a whole. Scientists around the world have discovered many things Scientists around the world have discovered many things about our planet by working together and sharing their about our planet by working together and sharing their findings.findings.

Some facts are well known. For instance, Earth is the Some facts are well known. For instance, Earth is the third planet from the Sun and the fifth largest in the solar third planet from the Sun and the fifth largest in the solar system. Earth's diameter is just a few hundred kilometers system. Earth's diameter is just a few hundred kilometers larger than that of larger than that of VenusVenus. The four seasons are a result . The four seasons are a result of Earth's axis of rotation being tilted more than 23 of Earth's axis of rotation being tilted more than 23 degrees.degrees.

EarthEarth

Distance from the Sun: 149,597,890 kmDistance from the Sun: 149,597,890 kmVolume: 1,083,200,000,000 km3Volume: 1,083,200,000,000 km3Mass: 5,973,700,000,000,000,000,000,Mass: 5,973,700,000,000,000,000,000,

000 kg000 kg

Earth’s MoonEarth’s Moon


The regular daily and monthly rhythms of The regular daily and monthly rhythms of Earth'sEarth's only natural satellite, the Moon, have guided only natural satellite, the Moon, have guided timekeepers for thousands of years. Its influence timekeepers for thousands of years. Its influence on Earth's cycles, notably tides, has also been on Earth's cycles, notably tides, has also been charted by many cultures in many ages. More charted by many cultures in many ages. More than 70 spacecraft have been sent to the Moon; than 70 spacecraft have been sent to the Moon; 12 astronauts have walked upon its surface and 12 astronauts have walked upon its surface and brought back 382 kg (842 pounds) of lunar rock brought back 382 kg (842 pounds) of lunar rock and soil to Earth. and soil to Earth.

Earth’s MoonEarth’s Moon The presence of the Moon stabilizes Earth's The presence of the Moon stabilizes Earth's

wobble. This has led to a much more stable wobble. This has led to a much more stable climate over billions of years, which may have climate over billions of years, which may have affected the course of the development and affected the course of the development and growth of life on Earth.growth of life on Earth.

Scientists believe that the Moon was formed Scientists believe that the Moon was formed approximately 4.5 billion years ago (the age of approximately 4.5 billion years ago (the age of the oldest collected lunar rocks). When the the oldest collected lunar rocks). When the Moon formed, its outer layers melted under very Moon formed, its outer layers melted under very high temperatures, forming the lunar crust, high temperatures, forming the lunar crust, probably from a global "magma ocean."probably from a global "magma ocean."


Distance from Earth: 384,400 kmDistance from Earth: 384,400 kmVolume: 21,970,000,000 km3Volume: 21,970,000,000 km3Mass: 73,483,000,000,000,000,000,000 Mass: 73,483,000,000,000,000,000,000

kgkg

MarsMars

MarsMars The red planet Mars has inspired wild flights of imagination over the The red planet Mars has inspired wild flights of imagination over the

centuries, as well as intense scientific interest. Whether fancied to centuries, as well as intense scientific interest. Whether fancied to be the source of hostile invaders of Earth, the home of a dying be the source of hostile invaders of Earth, the home of a dying civilization, or a rough-and-tumble mining colony of the future, Mars civilization, or a rough-and-tumble mining colony of the future, Mars provides fertile ground for science fiction writers, based on seeds provides fertile ground for science fiction writers, based on seeds planted by centuries of scientific observations. planted by centuries of scientific observations.

We know that Mars is a small rocky body once thought to be very We know that Mars is a small rocky body once thought to be very Earth-like. Like the other "terrestrial" planets - Earth-like. Like the other "terrestrial" planets - MercuryMercury, , VenusVenus, and , and EarthEarth - its surface has been changed by volcanism, impacts from - its surface has been changed by volcanism, impacts from other bodies, movements of its crust, and atmospheric effects such other bodies, movements of its crust, and atmospheric effects such as dust storms. as dust storms.

MarsMars It has polar ice caps that grow and recede with the It has polar ice caps that grow and recede with the

change of seasons; areas of layered soils near the change of seasons; areas of layered soils near the Martian poles suggest that the planet's climate has Martian poles suggest that the planet's climate has changed more than once, perhaps caused by a regular changed more than once, perhaps caused by a regular change in the planet's orbit. Martian tectonism - the change in the planet's orbit. Martian tectonism - the formation and change of a planet's crust - differs from formation and change of a planet's crust - differs from Earth's. Where Earth tectonics involve sliding plates that Earth's. Where Earth tectonics involve sliding plates that grind against each other or spread apart in the seafloors, grind against each other or spread apart in the seafloors, Martian tectonics seem to be vertical, with hot lava Martian tectonics seem to be vertical, with hot lava pushing upwards through the crust to the surface. pushing upwards through the crust to the surface. Periodically, great dust storms engulf the entire planet. Periodically, great dust storms engulf the entire planet. The effects of these storms are dramatic, including giant The effects of these storms are dramatic, including giant dunes, wind streaks, and wind-carved features.dunes, wind streaks, and wind-carved features.

MarsMars

Distance from the Sun: 227,936,640 kmDistance from the Sun: 227,936,640 kmVolume: 163,140,000,000 km3Volume: 163,140,000,000 km3Mass: 641,850,000,000,000,000,000,000 Mass: 641,850,000,000,000,000,000,000

kgkg

JupiterJupiter

JupiterJupiter The most massive planet in our solar system, with four The most massive planet in our solar system, with four

planet-sized moons and many smaller moons, Jupiter planet-sized moons and many smaller moons, Jupiter forms a kind of miniature solar system. Jupiter forms a kind of miniature solar system. Jupiter resembles a star in composition. In fact, if it had been resembles a star in composition. In fact, if it had been about eighty times more massive, it would have become about eighty times more massive, it would have become a star rather than a planet. a star rather than a planet.

On January 7, 1610, using his primitive telescope, On January 7, 1610, using his primitive telescope, astronomer Galileo Galilei saw four small 'stars' near astronomer Galileo Galilei saw four small 'stars' near Jupiter. He had discovered Jupiter's four largest moons, Jupiter. He had discovered Jupiter's four largest moons, now called now called IoIo, , EuropaEuropa, , GanymedeGanymede, and , and CallistoCallisto. .

JupiterJupiter Galileo would be astonished at what we have learned Galileo would be astonished at what we have learned

about Jupiter and its moons in the past 30 years. Io is about Jupiter and its moons in the past 30 years. Io is the most volcanically active body in our solar system. the most volcanically active body in our solar system. Ganymede is the largest planetary moon and is the only Ganymede is the largest planetary moon and is the only moon in the solar system known to have its own moon in the solar system known to have its own magnetic field. A liquid ocean may lie beneath the frozen magnetic field. A liquid ocean may lie beneath the frozen crust of Europa. Icy oceans may also lie deep beneath crust of Europa. Icy oceans may also lie deep beneath the crusts of Callisto and Ganymede. In 2003 alone, the crusts of Callisto and Ganymede. In 2003 alone, astronomers discovered 23 new moons orbiting the giant astronomers discovered 23 new moons orbiting the giant planet, giving Jupiter a total moon count of 49 officially planet, giving Jupiter a total moon count of 49 officially named -- the most in the solar system. The numerous named -- the most in the solar system. The numerous small outer moons may be asteroids captured by the small outer moons may be asteroids captured by the giant planet's gravity.giant planet's gravity.

JupiterJupiter

Distance from the Sun: 778,412,020 kmDistance from the Sun: 778,412,020 kmVolume: 1,425,500,000,000,000 km3Volume: 1,425,500,000,000,000 km3Mass: 1,898,700,000,000,000,000,000,Mass: 1,898,700,000,000,000,000,000,

000,000 kg000,000 kg

SaturnSaturn

SaturnSaturn Saturn was the most distant of the five planets known to Saturn was the most distant of the five planets known to

the ancients. the ancients. In 1610, Italian astronomer Galileo Galilei was the first to In 1610, Italian astronomer Galileo Galilei was the first to

gaze at Saturn through a telescope. To his surprise, he gaze at Saturn through a telescope. To his surprise, he saw a pair of objects on either side of the planet. He saw a pair of objects on either side of the planet. He sketched them as separate spheres and wrote that sketched them as separate spheres and wrote that Saturn appeared to be triple-bodied. Continuing his Saturn appeared to be triple-bodied. Continuing his observations over the next few years, Galileo drew the observations over the next few years, Galileo drew the lateral bodies as arms or handles attached to Saturn.lateral bodies as arms or handles attached to Saturn.

In 1659, Dutch astronomer Christiaan Huygens, using a In 1659, Dutch astronomer Christiaan Huygens, using a more powerful telescope than Galileo's, proposed that more powerful telescope than Galileo's, proposed that Saturn was surrounded by a thin, flat ring. Saturn was surrounded by a thin, flat ring.

SaturnSaturn In 1675, Italian-born astronomer Jean-Dominique In 1675, Italian-born astronomer Jean-Dominique

Cassini discovered a 'division' between what are now Cassini discovered a 'division' between what are now called the A and B rings. It is now known that the called the A and B rings. It is now known that the gravitational influence of Saturn's moon Mimas is gravitational influence of Saturn's moon Mimas is responsible for the Cassini Division.responsible for the Cassini Division.

Like Jupiter, Saturn is made mostly of hydrogen and Like Jupiter, Saturn is made mostly of hydrogen and helium. Its volume is 755 times greater than that of helium. Its volume is 755 times greater than that of Earth. Winds in the upper atmosphere reach 500 meters, Earth. Winds in the upper atmosphere reach 500 meters, these super-fast winds, combined with heat rising from these super-fast winds, combined with heat rising from within the planet's interior, cause the yellow and gold within the planet's interior, cause the yellow and gold bands visible in the atmospherebands visible in the atmosphere

SaturnSaturn

Distance from the Sun: 1,426,725,400 kmDistance from the Sun: 1,426,725,400 kmVolume: 827,130,000,000,000 km3Volume: 827,130,000,000,000 km3Mass: 568,510,000,000,000,000,000,000,Mass: 568,510,000,000,000,000,000,000,

000 kg000 kg

UranusUranus

UranusUranus Once considered one of the blander-looking Once considered one of the blander-looking

planets, Uranus (pronounced YOOR un nus) has planets, Uranus (pronounced YOOR un nus) has been revealed as a dynamic world with some of been revealed as a dynamic world with some of the brightest clouds in the outer solar system the brightest clouds in the outer solar system and 11 rings. The first planet found with the aid and 11 rings. The first planet found with the aid of a telescope, Uranus was discovered in 1781 of a telescope, Uranus was discovered in 1781 by astronomer William Herschel. The seventh by astronomer William Herschel. The seventh planet from the Sun is so distant that it takes 84 planet from the Sun is so distant that it takes 84 years to complete one orbit. Uranus, with no years to complete one orbit. Uranus, with no solid surface, is one of the gas giant planets (the solid surface, is one of the gas giant planets (the others are Jupiter, Saturn, and Neptune). others are Jupiter, Saturn, and Neptune).

UranusUranus The atmosphere of Uranus is composed The atmosphere of Uranus is composed

primarily of hydrogen and helium, with a small primarily of hydrogen and helium, with a small amount of methane and traces of water and amount of methane and traces of water and ammonia. Uranus gets its blue-green color from ammonia. Uranus gets its blue-green color from methane gas. Sunlight is reflected from Uranus' methane gas. Sunlight is reflected from Uranus' cloud tops, which lie beneath a layer of methane cloud tops, which lie beneath a layer of methane gas. As the reflected sunlight passes back gas. As the reflected sunlight passes back through this layer, the methane gas absorbs the through this layer, the methane gas absorbs the red portion of the light, allowing the blue portion red portion of the light, allowing the blue portion to pass through, resulting in the blue-green color to pass through, resulting in the blue-green color that we see. that we see.

UranusUranus


000 kg000 kg

NeptuneNeptune

NeptuneNeptune The eighth planet from the Sun, Neptune was The eighth planet from the Sun, Neptune was

the first planet located through mathematical the first planet located through mathematical predictions rather than through regular predictions rather than through regular observations of the sky. (Galileo had recorded it observations of the sky. (Galileo had recorded it as a fixed star during observations with his small as a fixed star during observations with his small telescope in 1612 and 1613.) When Uranus telescope in 1612 and 1613.) When Uranus didn't travel exactly as astronomers expected it didn't travel exactly as astronomers expected it to, a French mathematician, Urbain Joseph Le to, a French mathematician, Urbain Joseph Le Verrier, proposed the position and mass of Verrier, proposed the position and mass of another as yet unknown planet that could cause another as yet unknown planet that could cause the observed changes to Uranus' orbit. the observed changes to Uranus' orbit.

NeptuneNeptune After being ignored by French astronomers, Le After being ignored by French astronomers, Le

Verrier sent his predictions to Johann Gottfried Verrier sent his predictions to Johann Gottfried Galle at the Berlin Observatory, who found Galle at the Berlin Observatory, who found Neptune on his first night of searching in 1846. Neptune on his first night of searching in 1846. Seventeen days later, its largest moon, Triton, Seventeen days later, its largest moon, Triton, was also discovered. was also discovered.

Nearly 4.5 billion kilometers from the Sun, Nearly 4.5 billion kilometers from the Sun, Neptune orbits the Sun once every 165 years. It Neptune orbits the Sun once every 165 years. It is invisible to the naked eye because of its is invisible to the naked eye because of its extreme distance from Earth. extreme distance from Earth.

NeptuneNeptune


000 kg000 kg

PlutoPluto

PlutoPluto

Once known as the smallest, coldest, and most Once known as the smallest, coldest, and most distant planet from the Sun, Pluto has a dual distant planet from the Sun, Pluto has a dual identity, not to mention being enshrouded in identity, not to mention being enshrouded in controversy since its discovery in 1930. On controversy since its discovery in 1930. On August 24, 2006, Pluto was downgraded from an August 24, 2006, Pluto was downgraded from an official planet to a dwarf planet. No spacecraft official planet to a dwarf planet. No spacecraft have yet visited Pluto. However, NASA launched have yet visited Pluto. However, NASA launched a mission called New Horizons that will explore a mission called New Horizons that will explore both Pluto and the Kuiper Belt region.both Pluto and the Kuiper Belt region.

PlutoPluto

Distance from the Sun: 5,906,380,000 kmDistance from the Sun: 5,906,380,000 kmVolume: 6,390,000,000 km3Volume: 6,390,000,000 km3Mass: 13,000,000,000,000,000,000,000 Mass: 13,000,000,000,000,000,000,000

kgkg

AsteroidsAsteroids

AsteroidsAsteroids Asteroids are rocky fragments left over from the Asteroids are rocky fragments left over from the

formation of the solar system about 4.6 billion years ago. formation of the solar system about 4.6 billion years ago. Most of these fragments of ancient space rubble - Most of these fragments of ancient space rubble - sometimes referred to by scientists as minor planets - sometimes referred to by scientists as minor planets - can be found orbiting the Sun in a belt between Mars can be found orbiting the Sun in a belt between Mars and Jupiter. This region in our solar system, called the and Jupiter. This region in our solar system, called the Asteroid Belt or Main Belt, probably contains millions of Asteroid Belt or Main Belt, probably contains millions of asteroids ranging widely in size from Ceres, which at 940 asteroids ranging widely in size from Ceres, which at 940 km in diameter is about one-quarter the diameter of our km in diameter is about one-quarter the diameter of our Moon, to bodies that are less than 1 km across. There Moon, to bodies that are less than 1 km across. There are more than 90,000 numbered asteroids. are more than 90,000 numbered asteroids.

AsteroidsAsteroids As asteroids revolve around the Sun in elliptical orbits, As asteroids revolve around the Sun in elliptical orbits,

giant Jupiter's gravity and occasional close encounters giant Jupiter's gravity and occasional close encounters with Mars or with another asteroid change the asteroids' with Mars or with another asteroid change the asteroids' orbits, knocking them out of the Main Belt and hurling orbits, knocking them out of the Main Belt and hurling them into space across the orbits of the planets. them into space across the orbits of the planets. Scientists believe that stray asteroids or fragments of Scientists believe that stray asteroids or fragments of asteroids have slammed into Earth in the past, playing a asteroids have slammed into Earth in the past, playing a major role both in altering the geological history of our major role both in altering the geological history of our planet and in the evolution of life on it. The extinction of planet and in the evolution of life on it. The extinction of the dinosaurs 65 million years ago has been linked to a the dinosaurs 65 million years ago has been linked to a devastating impact near the Yucatan peninsula in devastating impact near the Yucatan peninsula in Mexico.Mexico.

MeteoroidsMeteoroids


"Shooting stars" or meteors are bits of material "Shooting stars" or meteors are bits of material falling through Earth's atmosphere; they are falling through Earth's atmosphere; they are heated to incandescence by the friction of the heated to incandescence by the friction of the air. The bright trails as they are coming through air. The bright trails as they are coming through the Earth's atmosphere are termed meteors, and the Earth's atmosphere are termed meteors, and these chunks as they are hurtling through space these chunks as they are hurtling through space are called meteoroids. Large pieces that do not are called meteoroids. Large pieces that do not vaporize completely and reach the surface of the vaporize completely and reach the surface of the Earth are termed meteorites. Earth are termed meteorites.


Scientists estimate that 1,000 tons to more Scientists estimate that 1,000 tons to more than 10,000 tons of meteoritic material than 10,000 tons of meteoritic material falls on the Earth each day. However, falls on the Earth each day. However, most of this material is very tiny - in the most of this material is very tiny - in the form of micrometeoroids or dust-like grains form of micrometeoroids or dust-like grains a few micrometers in size. a few micrometers in size.

CometsComets

CometsComets Throughout history, people have been both Throughout history, people have been both

awed and alarmed by comets, stars with "long awed and alarmed by comets, stars with "long hair" that appeared in the sky unannounced and hair" that appeared in the sky unannounced and unpredictably. We now know that comets are unpredictably. We now know that comets are dirty-ice leftovers from the formation of our solar dirty-ice leftovers from the formation of our solar system around 4.6 billion years ago. They are system around 4.6 billion years ago. They are among the least-changed objects in our solar among the least-changed objects in our solar system and, as such, may yield important clues system and, as such, may yield important clues about the formation of our solar system. We can about the formation of our solar system. We can predict the orbits of many of them, but not all. predict the orbits of many of them, but not all.

CometsComets

Around a dozen "new" comets are Around a dozen "new" comets are discovered each year. Short-period discovered each year. Short-period comets are more predictable because they comets are more predictable because they take less than 200 years to orbit the Sun. take less than 200 years to orbit the Sun. Most come from a region of icy bodies Most come from a region of icy bodies beyond the orbit of Neptune. beyond the orbit of Neptune.

Kuiper beltKuiper belt

Kuiper beltKuiper belt

The Kuiper (pronounced Ki-Per) Belt is often The Kuiper (pronounced Ki-Per) Belt is often called our Solar System's 'final frontier.' This called our Solar System's 'final frontier.' This disk-shaped region of icy debris is about 4.5 to disk-shaped region of icy debris is about 4.5 to 7.5 billion km (2.8 billion to 4.6 billion miles), 30 7.5 billion km (2.8 billion to 4.6 billion miles), 30 to 50 Astronomical Units (AU). from our Sun. Its to 50 Astronomical Units (AU). from our Sun. Its existence confirmed only a decade ago, the existence confirmed only a decade ago, the Kuiper Belt and its collection of icy objects - Kuiper Belt and its collection of icy objects - KBOs - are an emerging area of research in KBOs - are an emerging area of research in planetary science. planetary science.

Dwarf PlanetsDwarf Planets

Dwarf PlanetsDwarf Planets

A "dwarf planet" is a celestial body that (a) A "dwarf planet" is a celestial body that (a) is in orbit around the Sun, (b) has is in orbit around the Sun, (b) has sufficient mass for its self-gravity to sufficient mass for its self-gravity to overcome rigid body forces so that it overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly assumes a hydrostatic equilibrium (nearly round) shape, (c) has not cleared the round) shape, (c) has not cleared the neighborhood around its orbit, and (d) is neighborhood around its orbit, and (d) is not a satellite.not a satellite.

The Oort CloudThe Oort Cloud

The Oort CloudThe Oort Cloud

The Oort Cloud is an immense spherical cloud The Oort Cloud is an immense spherical cloud surrounding our Solar System. Extending about surrounding our Solar System. Extending about 30 trillion kilometers (18 trillion miles) from the 30 trillion kilometers (18 trillion miles) from the Sun, it was first proposed in 1950 by Dutch Sun, it was first proposed in 1950 by Dutch astronomer Jan Oort. The vast distance of the astronomer Jan Oort. The vast distance of the Oort cloud is considered to be the outer edge of Oort cloud is considered to be the outer edge of the Solar System - where the Sun's orb of the Solar System - where the Sun's orb of physical and gravitational influence ends. physical and gravitational influence ends.

the solar system the solar system consists of the sun and those celestial objects bound to it by...

Documents