Solar System 101 | National Geographic

– Our solar system is oneof over 500 known solar systemsin the entire Milky Way galaxy. The solar system came into beingabout 4. 5 billion years ago, when a cloudof interstellar gas and dust collapsed,resulting in a solar
nebula, a swirling discof material that collided
to form the solar system. The solar system is locatedin the Milky Way’s Orion star cluster. Only 15% of stars in the
galaxy host planetary systems,and one of those stars is our own sun. Revolving around the
sun are eight planets. The planets are divided
into two categories,based on their composition,Terrestrial and Jovian. Terrestrial planets including
Mercury, Venus, Earth,and Mars, are primarily
made of rocky material. Their surfaces are solid,
they don’t have ring systems,they have very few or no moons,and they are relatively small. The smallest and closest
to the sun is Mercury,which has the shortest
orbit in the solar systemat about three Earth months. Venus is the hottest
planet, with temperaturesof up to 867 degrees
Fahrenheit, due to an atmosphereof carbon dioxide and
extensive lava flows. Next to this world of fire
is a world of water, Earth. The water systems on
this planet help createthe only known environment in the universecapable of sustaining life. The last of the terrestrial planets, Mars,might have also supported life
about 3. 7 billion years ago,when the planet had a watery
surface, and moist atmosphere. Beyond the four Terrestrial planetsof the inner solar system
lie the Jovian planetsof the outer solar system. The Jovian planets include
gas giants Jupiter and Saturnand ice giants Uranus and Neptune. The gas giants are
predominantly made of heliumand hydrogen, and the ice
giants also contain rock, ice,and a liquid mixture of
water, methane, and ammonia. All four Jovian planets
have multiple moons,sport ring systems, have no
solid surface, and are immense. The largest Jovian is
also the largest planetin the solar system, Jupiter. Nearby is Saturn, the solar
system’s second largest planet. Its signature rings are wide enoughto fit between Earth and the moon,but are barely a kilometer thick. Past Saturn are the ice
giants, Uranus and Neptune. The slightly bigger of
these ice giants, Uranus,is famous for rotating on its side. Next to Uranus is Neptune,
the outermost planetin the solar system, and
also one of the coldest. Orbiting the Terrestrial
planets is the asteroid belt,a flat disc of rocky
objects, full of remnantsfrom the solar system’s formation. From microscopic dust particles,to the largest known object,
the dwarf planet, Ceres. Another disc of space debris
lies much further out,and orbits the Jovian
planets, the icy Kuiper Belt. Apart from asteroids, the
Kuiper Belt is also hometo dwarf planets, such as Pluto,and is the birthplace of many comets. Beyond the Kuiper Belt is the Oort Cloud,a vast, spherical
collection of icy debris. It is considered the
edge of the solar systemsince that is where the gravitationaland physical influences of the sun end. Our solar system’s
particular configurationof planets and other celestial objects,all revolving around a life-giving star,make it a special place to call home.