A star and all of the objects that travel in orbit around it The area of space that is influenced...
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Transcript of A star and all of the objects that travel in orbit around it The area of space that is influenced...
A star and all of the objects that travel in orbit around it
The area of space that is influenced by the gravity of a star
Our solar system is just one of many others.
What is a Solar System?
The Sun Planets Dwarf Planets Satellites/Moons Comets Asteroids Meteoroids
Objects in Our Solar System
Layout of Our Solar System
Distance and size NOT to scale
Relative Sizes in our Solar System
All planets orbit the sun in almost-circular elliptical orbits on approximately the same plane (the ecliptic).
Dwarf Planets, comets, asteroids, and meteoroids also orbit the sun
Most Satellites/Moons orbit planets (some orbit dwarf planets or even asteroids)
Almost all planets, dwarf planets, and moons rotate and revolve counter-clockwise
Motions of our Solar System
In 2006, the IAU defined a planet as a celestial body that:◦Is in orbit around the sun◦Has sufficient mass to assume a (nearly)
round shape◦Has cleared the neighborhood around its
orbit
What is a Planet?
Two kinds of planets:Terrestrial Inner Planets Jovian Outer Planets
“Earth-like”◦Mercury◦Venus◦Earth◦Mars
“Jupiter-like”◦Jupiter◦Saturn◦Uranus◦Neptune
Gas Giants
Ice Giants
Terrestrial (Inner) Planets
Closer to the sun Relatively small size and mass as compared to
outer planets
Rocky surface Craters present to some degree on all inner
planets
Curiosity Rover’s Selfie on Mars
Feb. 2015 – NASA image
Jovian (Outer) Planets Further from the sun Very massive Gas Giants and Ice Giants Lower average density than terrestrial planets All have rings
2006 image from Keck Observatory
Jupiter
In 2006, the IAU defined a dwarf planet as a celestial body that:◦Is in orbit around the sun◦Has sufficient mass that it assumes a
(nearly) round shape◦Has NOT cleared the neighborhood
around its orbit◦Is NOT a satellite
What is a Dwarf Planet?
Smaller than planets Have “company” in their orbital areas Can have moons Most are located in
the Kuiper Belt, but Ceres is in the Asteroid Belt
Dwarf Planets
Bright spot? More to come,
as Dawn mission approaches Ceres this month
Ceres image taken by Dawn Spacecraft Feb. 19, 2015
A satellite (AKA-moon) is an object that revolves around a planet or dwarf planet (or an asteroid)
As of 2008, there are 176 confirmed moons in our solar system
Most are located around the outer planets
What is a Satellite?
Explorers’ Guide to the Solar System 16
Jupiter’s moon Io
Image taken by Galileo spacecraft in 2002
Small Bodies Many smaller objects also orbit the sun◦Asteroids◦Comets◦Meteoroids
Asteroids are small, rocky, and irregular (up to 1000 km)
Sometimes called “minor planets”
Most orbit in a region between the orbits of Mars and Jupiter known as the Asteroid Belt
Combined, they would be about half the size of Earth’s moon
Asteroids
Comets An ice and rock core
(nucleus) that melts as it approaches the sun and gets blown into space by solar wind pressure (coma and tail).
Highly elliptical orbits originate in deep space
Kitt Peak telescope imageof comet NEAT in 2004(NASA, NOAO, NSF, T. Rector, Z.Levay and L.Frattare)
Rosetta Mission to Comet On 12 November
2014, ESA's Rosetta mission soft-landed its Philae probe on comet 67P/ Churyumov-Gerasimenko
During the next phase of the mission, Rosetta will accompany the comet through perihelion in August 2015
Image taken by Rosetta 165 km from the center of Comet 67P, April 15, 2015
Meteoroids are small irregular grains of rock, most are asteroid pieces and comet dust (up to a few meters in diameter)◦If they collide with Earth’s atmosphere, they
form visible streaks of light as they burn up and are called meteors (shooting stars)
◦If a meteor reaches Earth’s surface, it is then classified as a meteorite
MeteoroidMeteorMeteorite
Their location ◦Meteoroid= space◦Meteor= Earth’s atmosphere◦Meteorite= Earth’s surface
What’s the only difference between a meteoroid, a meteor, and a meteorite?
Explorers’ Guide to the Solar System 24