the layout
DESCRIPTION
The Layout. Inner Rocky Planets Asteroid Belt Outer Gas Giants Kuiper Belt Oort Cloud. Planets. “Wandering Stars” or “Wanders” (Greek) Discovery of Uranus (1781) and Neptune (1846) Discovery of Pluto (1930) later reclassified as a dwarf planet - PowerPoint PPT PresentationTRANSCRIPT
The Layout
• Inner Rocky Planets
• Asteroid Belt
• Outer Gas Giants
• Kuiper Belt
• Oort Cloud
Planets
• “Wandering Stars” or “Wanders” (Greek)
• Discovery of Uranus (1781) and Neptune (1846)
• Discovery of Pluto (1930) later reclassified as a dwarf planet
• Discovery of Eris (2003) later reclassified as a dwarf planet
Planets
• International Astronomical Union (IAU) 2006 definition:
• a planet is a celestial body that– is in orbit around the Sun, – has sufficient mass to assume hydrostatic
equilibrium (a nearly round shape), and – has cleared the neighbourhood around its
orbit.
Rocky Planets
• Mercury
• Venus
• Earth
• Mars
Images: www.nasa.gov
Asteroids
• Orbit between Mars and Jupiter
• Rocky objects too small to be called planets
Images: www.nasa.gov
Gas Giant Planets
• Jupiter
• Saturn
• Uranus
• Neptune
Images: www.nasa.gov
Kuiper Belt
• Disk-shaped region past Neptune 30-50 AU from the Sun
• Similar to asteroid belt, but much larger—20 times as wide and 20–200 times as massive
• Kuiper Belt Objects (KBOs): Icy “asteroids”
Poor Pluto?
Images: http://web.gps.caltech.edu/~mbrown/dwarfplanets/
Dwarf Planets
• A "dwarf planet" is a celestial body that – is in orbit around the Sun, – has sufficient mass for its self-gravity to
overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape,
– has not cleared the neighbourhood around its orbit, and
– is not a satellite.International Astronomical Union (IAU) 2006
Dwarf Planets
• Orbits in the Asteroid Belt:– Ceres
• Orbits in the Kuiper Belt:– Pluto– Eris – MakeMake – Haumea
Image: www.nasa.gov
Comets
• “dirty snowballs”• Highly elliptical orbits
around the Sun• As they get close to
the Sun, the ices “melt” and trail out behind the comet making a “tail”
• “tails” always point away from the Sun
Image: http://spaceplace.jpl.nasa.gov/en/kids/phonedrmarc/2004_january.shtml
Images: www.nasa.gov
Oort Cloud
• Proposed in 1950 by Dutch astronomer Jan Oort
• Spherical shell of icy bodies surrounding the solar system
• Origin of “long period” comets (200+ years)