Science: Earth And Space - Chapter 10

Astronomy

The study of heavenly bodies

Solar system

The sun and all natural objects that orbit it.

Orbit

To circle around due to gravity.

Aristotle

Greek philosopher who popularized the idea that universe is geocentric.

Geocentric

(Earth centered).

Ptolemy

Ancient astronomer from Alexandria, Egypt, who adopted and expanded Aristotle's geocentric view in his book Almagest.

Nicolaus Copernicus

Polish astronomer who proposed the heliocentric theory.

Heliocentric

(Sun centered).

Galileo Galilei

Italian astronomer who built one of the first telescopes and used it in his astronomical investigations.

Johannes Kepler

Lutheran astronomer who developed the laws of planetary motion.

Ellipses

Ovals that planets orbit in.

Laws of planetary motion

Three laws formulated by Johannes Kepler to help explain observation of the planet's paths.

First Law of planetary motion

States that every planet orbits the sun in an ellipse.

Second Law of planetary motion

As a planet moves closer to the sun, it travels faster and as it moves farther away it slows down.

Third Law of planetary motion

The farther a planets distance from the sun, the longer it's period

Perihelion

Closest point of an orbit around the sun.

Aphelion

Most distant point of an orbit around the sun.

Period

The time it takes for a celestial body to complete one full cycle of a repeating motion.

Astronomical unit

Distance unit approximately equal to the distance between the earth and the sun.

Sir Isaac Newton

Scientist who discovered the law of universal gravitation.

Gravity

Force of attraction that exists between any two objects.

Laws of universal gravitation

Law stating that the strength of the gravitational force between two objects depends on their masses and the distance between them.

Interplanetary space

Space between the planets.

Vacuum

A space that does not contain any matter.

Planets

Object that orbits the sun, has enough gravity to be a sphere, and has removed small objects from its orbit.

Mercury

Closes planet to the sun, and the fastest on the solar system.

Venus

Second planet from the sun, which is often the brightest object in the night sky except for the moon; Known as the morning star and evening star, and the hottest planet in the solar system. It's axis is longer than it's orbit, and rotates backwards.

Retrograde

Rotation of a planet that moves backwardfrom, east to west.

Earth

Third planet from the sun; the only planet in the solar system that is suitable for life.

moon

Earth's only natural satellite.

satellite

An object that orbits another object.

maria

One of the moon's dark patches.

solar eclipse

Phenomenon that occurs when a new moon moves directly between the earth and the sun and blocks part or all of the sun from our view.

lunar eclipse

Phenomenon that occurs when the full moon passes through the earth's shadow and the moon darkens because it can no longer reflect the sun's light.

Mars

Fourth planet from the sun, known for its reddish-orange color.

Olympus Mons

The largest mountain (or volcano) on the solar system. Located in Mars.

Jupiter

Fifth planet from the sun; the largest planet in the solar system.

Great Red Spot

Biggest storm seen on the planet Jupiter.

Galilean satellites

Four largest moons of Jupiter, which were discovered by Galileo.

Saturn

Sixth planet from the sun and the second largest planet in the solar system.

Uranus

Seventh planet from the sun; first planet to be discovered that was not known since ancient times.

Neptune

Eight planet from the sun; the only planet discovered mathematically before it was seen.

dwarf planet

Object that orbit the sun, has enough gravity to be a sphere, has not removed certain smaller objects from around its orbit, and is not orbiting around another object.

Cere

First and largest asteroid discovered (Now considered a dwarf planet).

asteroid

Stony or metallic object that is smaller than the planets and orbits the sun.

asteroid belt

Large ring of asteroids located between the orbits of Mars and Jupiter.

Trojan asteroids

Two groups of asteroids that travel in Jupiter's orbit, one group in front of Jupiter and the other group behind.

near-earth asteroids

Any of a group of asteroids that are located in the inner solar system.

comet

Asteroid-sizzed object that is made of rock and frozen materials and forms a bright tail.

Edmond Halley

Astronomer who correctly calculated the orbit of the comet now known as Halley's comet.

Halley's comet

Comet named after Edmond Halley, who correctly calculated its orbit.

Nucleus

Central structure, such as the ice and dust forms the heart of a comet, the flattened ball at the center of a spiral galaxy, or the core of an atom.

Coma

Gas and dust cloud around the nucleus of a comet.

Tail

Highly reflective streamer emitted from a comet.

Short-period comet

Comet that has a period shorter than 200 years.

Long-period comet

Comet that has a period longer than 200 years.

Kuiper belt

Belt, similar to the asteroid belt but located outside Neptune's orbit, containing objects that resemble comet nuclei.

Meteoroids

Small chunk of rock or metal in space.

Meteor

Meteoroid that has entered the earth's atmosphere.

Meteor shower

Phenomenon that occurs when the earth passes through a meteoroid stream and meteors fall much faster than normal.

Fireball

Extremely bright meteor that can be observed over a much larger portion of the earth than an ordinary meteor.

Bolide

Fireball that explodes in midair.

Meteorites

Meteor that land on the earth's surface.

Celestial sphere

An imaginary, giant, hollow sphere with the Earth at its center and celestial objects on its inner surface.

Horizon

The line that separates the visible portion of the celestial sphere from the part that cannot be seen.

Celestial poles

Points on the celestial sphere that are directly overhead at Earth's poles.

Polaris

The North Star in Ursa Minor, located at the north celestial pole.

Celestial equator

The line on the celestial sphere halfway between the celestial poles and directly above Earth's equator.

Circumpolar

Refers to stars that are always above the horizon.

Ecliptic

The path on the celestial sphere that the sun follows throughout a year.

Zodiac

An imaginary band extending about $8^\circ$ on either side of the ecliptic, where the sun, moon, and planets appear.

Constellations

Any of the 88 zones into which modern astronomers divide the celestial sphere.

Asterisms

Small groups of stars used to form a picture or represent an object.

Ursa Major

The great bear constellation, which contains the Big Dipper.

Ursa Minor

the little bear constellation, which contains the Little Dipper and Polaris.

Regulus

Brightest star of Leo.

Boötes

Constellation that represents a herdsman and contains Arcturus.

Virgo

Constellation of a winged maiden holding a stalk of wheat; includes Spica.

Draco

Summer constellation that represents a dragon.

Lyra

Constellation of a harp that contains the star Vega.

Cygnus

Bright summer constellation of a swan that contains Deneb and the Northern Cross.

Summer Triangle

Prominent asterism formed by the stars Deneb, Vega, and Altair.

Antares

Brightest star of Scorpious

Teapot.

Brightest star of Sagittarius.

Vega

The brightest summer star.

Cassiopeia

A prominent constellation in the northern sky, easily recognizable by its characteristic "W" or "M" shape formed by five bright stars.

Alderamin

Brightest star of Cepheus

Andromeda

A large constellation in the northern sky named after a mythological princess.

Great Square

A prominent asterism formed by four bright stars, three belonging to the constellation Pegasus and one belonging to Andromeda, forming a large geometric square in the autumn sky.

Pegasus

A large northern constellation named after the mythical winged horse, best known for containing the Great Square asterism.

Perseus

A northern constellation named after the Greek mythological hero, well-known for hosting the variable star Algol.

Algol

Star in the constellation Perseus whose brightness noticeably dims and brightens in a predictable pattern as one star passes in front of the other.

Orion

Is one of the most prominent and recognizable constellations in the night sky, named after the mythical hunter in Greek mythology.

Orion Nebula

A bright diffuse nebula situated in the Milky Way, located just south of Orion's Belt, and one of the most actively studied star-forming regions visible to the naked eye.

Canis Major

A constellation in the southern celestial hemisphere representing the larger of Orion's two hunting dogs, notable for containing Sirius, the brightest star in the night sky.

Sirius

A star that can be found by tracing a line from Orion's belt.

Gemini

A prominent constellation of the zodiac, traditionally representing the celestial twins

Castor & Pollux

The two brightest stars in the constellation Gemini, named after the twin brothers from Greek and Roman mythology.

Taurus

A large and prominent zodiac constellation representing a bull, featuring notable landmarks like the bright star Aldebaran and the Pleiades star cluster.

Aldebaran

A massive orange giant star located in the constellation Taurus that marks the fiery "eye" of the bull; it is one of the brightest stars in the night sky.