Download Types of Planets and Stars

Types of Planets and
Stars
John Phillips
Mrs. Cooper/NWRMS Science Bowl
September 1, 2014
History of Astronomy and Modern
Astronomy
 Astronomy is the study of the sun, moon, stars, planets, comets,
gases, galaxies, dust, and non-earthly bodies.
 Pythagoras, a Greek philosopher and mathematician, recorded
his first theories about stars. Some of his best theories were
about the “morning star” and the “evening star,” which was
Venus, and the idea that the Earth was in motion.
 Modern astronomy defines a star as “a self-luminous body
consisting of gas held together by gravity in which is generated
by nuclear fusion.”
 It defines a planet as “a non-luminous celestial body larger than
an asteroid or comet illuminated by a star, which it revolves
around.”
Young Stars
 Protostars -- what is present before a true star forms. It is a
collection of gases and dust that have collapsed down from
large molecular clouds. This phase lasts about 100,000
years. The heat comes from gravitational heating, as nuclear
fusion has not started yet.
 T Tauri stars -- do not have enough pressure and
temperature to generate nuclear fusion, but they resemble
main sequence stars. They are about the same temperature,
but they are slightly bigger than main sequence stars. They
have more sunspots and X ray flares as well as very powerful
stellar winds. They will remain like this for about 100 million
years.
Middle-Aged Stars
 Main Sequence Stars -- make up the majority of stars in the
universe. Earth’s sun is a main sequence star. These stars
vary in size, mass, and brightness, but they all convert hydrogen
into helium, also known as nuclear fusion. While our sun will
spend 10 billion on its main sequence, a star ten times as
massive will stick around for only 20 million years.
 Red Dwarf -- most common stars in the universe. These stars
are main sequence stars that have very little mass and are
cooler than stars like Earth’s sun. Because of this, they use
hydrogen more slowly, which allows them to burn longer than
most stars. Its lifetime, 80-100 billion years, is older than the
universe.
 Super Giants -- because of their size, they use hydrogen more
quickly than most stars, and they live only 10-20 million years.
When they run completely out of fuel, they explode in a violent
supernova, which disintegrates the star.
Old Stars
 Red Giant – the main sequence star runs out of hydrogen at
its core, it swells up to take in extra elements such as helium
in a small band around the star.
 White Dwarf – if a main sequence star does not explode in a
super nova, it runs out of fuel and no more nuclear fusion
occurs within the star. These stars are basically stars that
are cooling down.
Terrestrial Planets
 Terrestrial planets are known as the inner rocky planets.
These planets are small in size and mass and have high
density. They are made mostly of rock and metal, and they
generally have solid surfaces with few to no moons.
Terrestrial planets are located close to the sun like Mercury,
Earth, and Venus.
Jovian Planets
 Jovian planets are knows as the gas giants. These planets
are high in size and mass and have low density. They are
made mostly of hydrogen and helium with no solid surface
and many moons. These planets can have rings around
them. Jovian planets are located further from the sun than
terrestrial, but are not necessarily colder. Examples of these
planets are Jupiter and Saturn.
Ice Giants
 Ice giants have a lower mass, size and hydrogen/helium
content than Jovian planets. These planets have rings much
like the Jovian planets. They are located in the furthest
reaches of the solar system. Examples of these are Neptune
and Uranus, and for many scientists, Pluto, which some feel
is still a planet.
Works Cited
Cain, Fraser. "Types of Stars." Universe Today RSS. Universe
Today, 28 Jan. 2009. Web. 06
Aug. 2014.
"Our Solar System." The Solar System: The Sun, Planets, Dwarf
Planets, Moons, Asteroids,
Comets, Meteors, Solar System Formation. National
Earth Science Teachers Association,
2012. Web. 06 Aug. 2014.
"Types of Solar System Planets." Types of Solar System Planets.
The Nebraska Astronomy
Project/University of Nebraska, 12 June 2014. Web. 06
Aug. 2014.