Space Glossary Terms Chapter 7

-any object that exists in space

EXAMPLE: a planet, a star, or the Moon

NOTE: studied by celestial priests and priestesses

-a scientist who studies astronomy, which is the study of the night sky

NOTE: the Mesopotamians were the first astronomers whom we have evidence of detailed astronomical observations

-the time it takes for an object to orbit around another object; Earth's revolution around the Sun is 365.24 days

• NOTE: 365.24 is the amount of days in an Earth year
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-the turning of an object around an imaginary axis running through it

NOTE: one day (24 hours) is the average time it takes Earth to make on rotation

-a group of stars that seem to form a pattern in the sky

EXAMPLE: Orion (the hunter), Ursa Major (the Great Bear) and Libra (the scales of justice) are all constellations in the sky

NOTE: constellations look close together as they lie on the same line of sight when in reality they may be light-years apart

-the distance that light travels in one year, about 9.5x10¹²km

NOTE: light travels at the speed of 300 000 km/s

-the brightness of a star as seem from Earth

EXAMPLE: Sirius is the brightest star in the sky 

NOTE: in a star map, the larger the dot the brighter the star is

-a prominent pattern or group of stars, typically having a popular name but smaller than a constellation.

-two stars of the Big Dipper in Ursa Major, through which a line points nearly to the Pole Star

NOTE: Polaris is the current north star

-a star above the horizon at all times in a given latitude

-the highest point reached by a celestial or other object

-the rising and falling of ocean waters as a result of the Moon's gravity and Earth's gravity

-the monthly progression of changes in the appearance of the Moon, which result from different portions of the Moon's sunlit side being visible from Earth

NOTE: main phases of the moon: new Moon, waxing crescent, first quarter, waxing gibbous, full Moon, waning gibbous and third quarter

-the phenomenon in which the full Moon passes into Earth's shadow

NOTE: if the moon passes through Earth's umbra, a total lunar eclipse occurs, if the Moon passes through only the penumbra or part of the umbra, a partial lunar eclipse occurs

NOTE: during a total lunar eclipse the Moon sometimes looks reddish

-the phenomenon in which the shadow of the Moon falls on Earth's surface (only happens during a full Moon)

NOTE: if you are in a location where the umbra touches Earth's surface you will see a total solar eclipse, if you are in a location where the penumbra touches Earth's surface you will see a partial solar eclipse

-because the earth is tilted as it makes its yearly journey around the sun. The Earth's axis is tilted at an angle of 23.5 degrees. This means that the Earth is always "pointing" to one side as it goes around the Sun.

EXAMPLE: in the summer months the northern hemisphere is tilted toward the Sun and is the winter months the northern hemisphere is tilted away from the Sun. The opposite happens in the Southern hemisphere. 

-an object that orbits one or more stars (and is not a star itself), it is spherical, and does not share its orbit with another object

Mercury: rocky ball covered in craters, closest to Sun, no atmosphere

Venus: size and composition similar to Earth, thick clouds, atmosphere contains sulfur, carbon dioxide and nitrogen

Earth: third from the Sun, life, water in 3 phases, atmosphere contains nitrogen, oxygen and water vapour

Mars: rusty colour "red planet", volcano, dust storms/canyon/hurricanes, two polar ice caps, thin atmosphere contains carbon dioxide

Jupiter: largest planet, red spot (storm in the clouds of hydrogen and helium), shortest day, rings made of ice particles

Saturn: rings, atmosphere contains hydrogen and some helium

Uranus: gas giant, ring system, blue-green colour (methane gas), atmosphere contains hydrogen and helium, flipped on its side so it appears to be rolling through its orbit

• Neptune: outermost planet, third most massive, darker blue than Uranus, ring system
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-a group of planets that circle one or more stars

NOTE: the Sun's gravitational pull keeps the objects in the solar system in orbit around the Sun

-the movement of an object in the sky, usually a planet, from east to west, rather than in its normal motion from west to east

EXAMPLE: produced when Earth catches up with and passes an outer planet in its orbit. Every time Earth catches up to an outer planet and moves between the outer planet and the Sun, the planet appears to make a looping motion 

-the average distance between Earth and the Sun, about 150x10⁶km

NOTE: Earth is 1 AU from the Sun

-the average distance between the Sun and an object that is orbiting the Sun

NOTE: the orbital radius is expressed in astronomical units

-a theory that was developed by philosophers in Ancient Greece and was named after the philosopher Claudius Ptolemy who lived circa 90 to 168 A.D. It was developed to explain how the planets, the Sun, and even the stars orbit around the Earth

-a theory that places the Sun as the center of the universe, and the planets orbiting around it. The heliocentric model replaced the geocentric model, which is the belief that the Earth is the center of the universe

-an object composed of rocky material, ice, and gas; comes from the Kuiper Belt and Oort Cloud

-a small object that ranges in size from a tiny speck, like a grain of sand, to 500km wide; most asteroids originate in the asteroid belt between Mars and Jupiter

-a piece of rock moving through space

-a meteoroid that hits Earth's atmosphere and burns up

-a meteorite that is large enough to pass through Earth's atmosphere and reach the ground, without being totally burned up

-any minor planet in the Solar System that orbits the Sun at a greater average distance (semi-major axis) than Neptune