Astro 1010 Final Exam Study Guide Notes

Located between the orbits of Mars and Jupiter.
Asteroids are primarily composed of metals and/or carbon-rich rock.
The inner and outer edges are determined by orbital resonances with Jupiter.
- Gaps within the asteroid belt with few objects are also due to orbital resonances.
- Jupiter's gravity prevented the formation of a large, single object in this region.
The asteroid belt is less crowded than commonly thought with widely spaced objects, making collisions rare.
The total mass of the main belt is only a fraction of the Earth's moon.

The only dwarf planet within the asteroid belt.
Contains 1/3 of the main belt's mass.
The only object massive enough to have a spherical shape; other objects are irregularly shaped.
Initially considered a planet upon discovery before other objects were found, then reclassified.

A large group of asteroids located outside the main belt, specifically in the L4 and L5 Lagrangian points of Jupiter.

Extends beyond the orbit of Neptune, closer to the sun than the Oort cloud.
Kuiper Belt Objects (KBOs) are mostly icy rather than rocky or metallic, similar in composition to comets.
The Kuiper belt is the origin of short-period comets (T < 200 years).
The inner and outer edges are determined by orbital resonances with Neptune.
Neptune's gravity prevented a large, single object from forming in the Kuiper Belt.
At least four dwarf planets are found here, with more candidates: Pluto, Eris, Makemake, and Haumea.

Has five moons, including Charon, which is half the size of Pluto.
Initially considered a planet before being reclassified as a dwarf planet when other objects were discovered in the belt.
Pluto's orbit crosses that of Neptune but will never collide because of a 2:3 orbital resonance. Its orbit is inclined about 17 degrees from the main plane of the planets.

Slightly more massive than Pluto; its discovery led to the creation of the "dwarf planet" classification.

A spherical distribution of icy objects at the solar system's edge.
The origin of long-period comets (T > 200 years).
Objects formed in the main disk of the solar system but were scattered into highly elliptical and randomly oriented orbits by the gas giants early in the solar system's history.

Two main populations:
- Long-period comets (T > 200 years) have highly inclined orbits and originate from the Oort cloud.
- Short-period comets (T < 200 years) have orbits in the main plane of the solar system and come from the Kuiper Belt.
Only a few comets enter the inner solar system; most remain in the Kuiper Belt or Oort cloud.
Comets are frozen lumps of ice when far from the sun, forming comas and tails as surface ice sublimates when closer to the sun.
- Comas form at a minimum distance of 3-5 AU from the sun.
- Tails form at a minimum distance of about 1 AU.
Comets have two tails: a plasma tail pointing directly away from the sun and a dust tail that curves away.
Satellite exploration of comets:
- Deep Impact: Fired a rocket at a comet and observed spectral features of the debris.
- Stardust: Flew through the coma of a comet and returned samples to Earth.
- Rosetta: Deployed a lander on a comet's surface, with limited success.
Meteor showers occur when Earth passes through the orbit of a comet.

Four main methods for detecting planets around other stars:
- Direct Imaging: Used for planets in wide orbits around nearby stars.
- Astrometry: Detects the slight motion of a star caused by a planet's gravitational pull.
- Doppler Shifts: Looks for blueshifts/redshifts in a star's spectra as a planet pulls on it.
- Transits: Detects dips in a star's luminosity when a planet passes in front of it.
The first extrasolar planet was found around a pulsar by observing offsets in the timing of its pulsations due to the planet's gravity.

Has found thousands of extrasolar planets using the transit method.
Planets are common, with rocky Earth-sized planets being more common than gas giants.
On average, every star has at least one planet.
Planets have been found in multi-star systems and orbiting single stars.

The range of distances around a star where a planet with an atmosphere can support liquid water on its surface.
Habitable zones are farther from hot, high-mass stars and closer to cooler, low-mass stars.
About 1/5 of sun-sized stars have an Earth-sized planet in their habitable zone.
High-mass stars may be less hospitable to life because they have short lifespans.
Low-mass stars may be less hospitable because planets in their habitable zones are likely tidally locked.

An intermediate class of objects between gas giants and stars, lacking sufficient mass to sustain nuclear fusion.

Objects that formed in orbit around a star but were ejected, now orbiting the galaxy on their own.