Lecture 35: Dwarf Planets

These flashcards cover key vocabulary and definitions related to dwarf planets and their classifications, discoveries, and other celestial phenomena discussed in the lecture.

Dwarf Planets

Astronomical bodies that orbit the Sun and are similar to planets but do not clear their neighboring region of other objects.

Pluto

A celestial body in the Kuiper Belt, reclassified as a dwarf planet in 2006.

Ceres

The first dwarf planet to be discovered, found by Giuseppe Piazzi on January 1, 1801.

Eris

A dwarf planet larger than Pluto, discovered in 2005.

Haumea

A dwarf planet known for its elongated shape and rapid rotation.

Makemake

A dwarf planet discovered in 2005 and named after a Rapa Nui god.

IAU Definition of a Planet

A planet must orbit the Sun, be spherical, and have cleared its orbit of debris.

Trojans

Asteroids that share an orbit with a planet, often found in groups at stable points known as Lagrange points.

Gravitational Influence

The effect that a celestial body exerts on another due to its mass, used in discovering Neptune.

Terrestrial Planets

Planets that are primarily composed of rock and metal, including Mercury, Venus, Earth, and Mars.

Gas Giants

Plenets composed mostly of hydrogen and helium, including Jupiter and Saturn.

Ice Giants

Planets that contain a larger proportion of 'ices' (water, ammonia) in their composition, such as Uranus and Neptune.

Orbits

The curved path of celestial bodies as they revolve around a star.

Asteroid Belt

The region of space between the orbits of Mars and Jupiter that contains many small, rocky bodies.

Historical Definitions of a Planet

The evolving criteria for what constitutes a planet, ranging from 'wandering star' to modern definitions requiring orbital clearance.

Evolution of Pluto's View

The progression of observations of Pluto from its discovery in 1930 to detailed exploration by New Horizons in 2015.

Wandering Stars

Ancient term for celestial bodies (Sun, Moon, Mercury, Venus, Mars, Jupiter, Saturn) that appeared to move across the sky.

William Herschel

Astronomer who discovered Uranus in 1781, expanding the known solar system.

Uranus

The planet discovered by William Herschel in 1781, notable as the first planet found with a telescope.

Vesta

A large asteroid and protoplanet residing in the asteroid belt.

Pallas

The second asteroid ever discovered, found in 1802, and one of the largest objects in the asteroid belt.

Juno

An asteroid discovered in 1804, residing in the asteroid belt.

Hygiea

A large asteroid discovered in 1849, one of the most massive objects in the main asteroid belt.

Urbain Le Verrier

French mathematician who accurately predicted the position of Neptune through gravitational calculations in 1845-1846.

Neptune

The eighth planet from the Sun, discovered in 1846 based on predictions from its gravitational effect on Uranus.

New Horizons Mission

A NASA spacecraft launched in 2006 that performed the first close flyby of Pluto and its moons in 2015.

Charon

The largest natural satellite of Pluto, which is almost half its size.