astronomy chapter 9

Asteroid

Small leftovers from solar system formation made of rock in metal they reside mostly in the asteroid belt

Formed inside the frost line

Comets

Are made of ices with rock and metal mixed in they are found mostly in the kuiper belt and the Oort cloud

Formed outside the frost line

Dwarf planets

Largest comets and asteroids (ceres, Pluto and eris) They are large enough to resemble planets in their behaviors, but are too small to dominate their regions of the solar system and are therefore found among the swarms of bodies in the asteroid belt and the kuiper belt.

Meteor versus meteorite

A meteor is a piece of debris that has entered our atmosphere and is glowing from the heat of entry

A meteorite is what is left of the debris after it hits the ground

Primitive meteorites

Intact leftovers of the solar nebula they contain rocks and metals mixed together, as well as carbon compounds in some cases

Processed meteorites

Have undergone differentiations in larger asteroids as a result, they are made up of either metals or rocky material rather than a mix of the two

The asteroid belt

It lies between the orbits of Mars and Jupiter. It exists because of orbital residence with Jupiter. Jupiter‘s gravitational influence increases the eccentricities of objects, making their collisions occur at high speeds. This keeps them from clumping together and forming a planet. It tends to make the asteroids break apart when they collide.

The coma and tails of a comet

They are produced by ices warming and sublimating off the surface as these ices turn to gas and carried away in the tail by solar wind (straight back from the sun) they escape the nucleus (the solid icy part of the comet in the middle) carrying dust with them in the dust tail which curves slowly away from the comet because the pressure of sunlight is so small compared to that of solar wind. The third tale of larger particles is the source of meteor showers.

Meteor showers

They occur when earth passes through a stream of pea size debris left behind by a comet

Kuiper belt

Similar to the asteroid belt, except that it is beyond the orbit of Neptune and is filled with ice bodies rather than rocky and metallic ones

Comments probably formed in the region of the solar system or close to it

Leftovers from the outer edges of the original solar nebula, they haven’t moved much since their formation

Oort belt

A spherical halo of comets well outside of the orbits of the planet, while comets in the kuiper belt have orbits that are nearly in the plane of the solar system and go around the sun in the “forward” direction Oort cloud comets often orbit on highly inclined orbits in any direction comets that are now in the oort cloud were probably flung there early in the solar system’s life by Jupiter

Pluto

Is significantly smaller than any of the planets and is made of ice and rock. This means that it does not fit into either the Jovian class or the terrestrial class of planets Pluto possesses a thin atmosphere that may freeze to the surface as a dwarf planet moves farther from the sun along its orbit. It’s orbit is also very elliptical and inclined relative to the plane of the solar system in spite of the fact that Pluto‘s orbit takes it inside the orbit of Neptune for part of the time, the two will never collide because Pluto and Neptune are a 3 to 2 resonance which puts Neptune far away when Pluto crosses Neptune‘s orbit.

Pluto‘s moon charon is slightly more than 1/10 the mass of Pluto, which gives these bodies the largest moon to planet ratio in the solar system. Evidence suggests that Cheron was formed in a giant impact the same way we think earths moon was formed.

Dinosaurs mass extinction

A worldwide layer of iridium that was laid down at that time. Iridium is rare on earth surface, but more common in comets and asteroids because the layer exists all around the globe. Something had to have brought the iridium to earth surface

The layer that contains the iridium also contains other elements, rare on earths surface In addition, we see such droplets that appear to have been formed by solidifying molten rock, and “shocked quartz,” crystals that show evidence of having experienced high temperatures and high pressures, we find a shocked quartz at known impact sites such as meteor crater, the soot points to global fires that would likely have caused by the hot impact debris. There is also a large crater called chicxulub on the Peninsula, which is the right size and age to be the result of the same impact event.

The impact could have caused global wildfires, dust and smoke blocking sunlight and thus making the planet, colder and choking off photosynthesis and acid rain and changing chemistry in the atmosphere and oceans

Jovian planets influence on earth

They have profoundly affected the orbits of small bodies through the action of orbital resonance. Jupiter affects the asteroid belt and Neptune affects the kuiper belt in the case of the asteroid belt, the Jovian influence prevented the formation of a terrestrial planet. in both of these cases resonance further nudge the objects into very elliptical orbits, which can result in collisions with the other planets. in the case of the Oort cloud, close gravitational encounters between icy planetesimals and the Jovian planets flung the comets outward to huge distances where they formed the Oort cloud. Nudges from other stars affected their orbits enough that most comets never reenter the inner solar system