Lecture 14: Oort Cloud, Comets, Gravitational Tug

Oort Cloud

The Oort Cloud is a hypothetical spherical shell of icy objects that is believed to exist in the outermost reaches of our solar system, serving as a source of long-period comets.

Kuiper Belt Objects Definition

Kuiper Belt Objects (KBOs) are small celestial bodies located in the Kuiper Belt, a region of the solar system beyond the orbit of Neptune, consisting primarily of icy and rocky debris.

A Kuiper Belt Object that is near Neptune

Pluto

Pluto is different from other gas giants because…

Pluto is classified as a rocky planet because it has a solid surface composed of ice and rock, unlike gas giants which lack a definitive solid surface and are primarily composed of gases. Inside Neptune’s orbit.

Comets

• highly elliptical orbits

• Nuclear of Rock and Ice (Dirty Snowball)

• Near the Sun it sublimates, debris falls off

• Tail points away from Sun

Parts of a comet

• Two Tails: plasma and dust tail (gyesers, etc) point away from Sun

• Hydrogen envelope

• nucleus

• coma

How do comet’s tails are affected by the Sun?

• Dust tail is pushed by sunlight, solar radiation

• Plasma tail is swept back by solar wind

Do comets last forever?

no, can be

• torn apart by tidal force

• collision

How do meteor showers happen?

• when Earth crosses the comet’s orbit

• ejects small particles that cause meteor showers

• comet dust is sprinkled thorughout inner solar system

How exoplanets are found?

use indirect methods

indirect methods to find exoplanets:

• observe motion of a star and detect gravitational tugs or orbiting planets

  • observing changes in star’s brightness when a planet passes in front of the star as viewed from Earth (Eclipsed)

Gravitational Tug

Sun experiences tug from gravitational tug force of other planets

• center of mass changes

Doppler effect and gravitational tug

redshifted when going away from Earth, blueshifted when towards Earth