Planets (29.1-29.3 + more current research) P. P. Solar System part 1 Planets (29.1-29.3 + more current research)

Some vocabulary prior to starting: Planitesimal: “PLANET CRUMBS”. Solid Objects that sit/float with other debris in disk-shaped clouds that surround our solar system. These merge together to form: Protoplanet: “COMPRESSING CRUMBS”A moon-sized “baby” planet that is still in the process of pulling matter towards itself and building in size through gravity. Dwarf Planet: “MINI PLANET” Smaller bodies that are trapped by the suns’ gravity, but are not moons and are not real planets because they cross the orbital pathway of others.

MODERN THEORIES ABOUT PlanetARY BODIES: Planitesimals Protoplanet Planet Dwarf Planet

Our Solar System ≈ 4.6 Billion Years Old Soon after the sun was thought to have formed, clouds of gas and dust around the new sun started to cool and condense to form protoplanets. Protoplanets could cool or collide together to form dwarf or regular planets. The planets near the sun eventually had their atmospheres / gas layers burned away, but the outer planets retained their gas composition and original size. Video: Solar System Development

Our planets are divided into two groups: Terrestrial : Solid surfaces, higher temperatures, little to no moons, small sizes, closest to sun Gas Giants (Jovian) : Large sizes, gasseous/liquid surfaces, many moons, colorful, farthest from sun

All planets outside of earth exhibit retrograde motion Any planet with an orbital pathway bigger than earth will appear to make a “loop-de-loop” in the night sky as seen from earth.

Other objects also remained from that cloud. . . There is an ASTEROID BELT between Mars and Jupiter, which is thought to be the “crumbs” of a planet body that was impacted. The KUIPER BELT is a disk-shaped belt of smaller planitesimals that are outside of Neptune. Video (C) The OORT CLOUD is a very very distant sphere of icy bodies (comets, etc.) that surround the solar system. It is thought to be attached to the Kuiper Belt.

(A) (B) (C)

Among the “crumbs” of the Kuiper Belt are many minor/dwarf planets, or planitesimals (134,000 +!) Pluto got “demoted” to a group of 5 dwarf planets (that probably reside in the Kuiper Belt) in 2006 by a scientific board called the IAU. --its orbit crossed other orbits --too small --different composition --really eccentric/oval orbit

Basic “factoids” about each planet: Mercury = smallest Venus = has runaway “greenhouse” effect Mars = The “red” planet; being explored for supporting life Jupiter = Largest , most moons (65+) , red spot is largest atmospheric storm Saturn = Colorful rings, density less than water Uranus = Horizontal/sideways axis, dim, slow Neptune = blue planet, active weather patterns, last planet

MARS: Is there anybody out there? Mars is being explored by the “Curiosity” Rover from NASA. Possible evidence of past life conditions there: riverbeds/flowing water erosion marks, fossilized bacteria, plains indicating ancient rivers or lakes, clay minerals which form in the presence of water, icy clouds in the sky.

The current obstacles: The atmospheric composition is not able to sustain life, and it’s also too thin Daytime temperatures at the equator reach 70 Degrees (F), but get down to -200 degrees at night!

Something Real: INTERNATIONAL SPACE STATION Video: Space Station 250 miles up Like a 5-bedroom home for astronauts, also equipped with science labs Many countries built it/use it People have continuously lived in it since 2000

Measuring Distance in our Solar System We use a unit called the “AU” = Astronomical Unit. This unit is equal to the distance between the SUN and EARTH ( ~93,000,000 mi) For instance, Mars is 1.38 AU from the sun (1 and 38/100 of the distance between the Earth and Sun)