Unit 2 Vocabulary

Accretion

• rapid decrease in size or amount

• slow growth in size or amount

• sudden change in shape

• immediate reduction in quantity

Asteroid

• a small rocky body orbiting the sun

• a large gas giant planet

• a comet made of ice and dust

• a satellite orbiting a planet

Summer solstice

• When one hemisphere experiences the longest day of the year due to Earth's maximum tilt towards the sun

• When the sun is directly above the equator, resulting in equal day and night

• When the days start getting shorter as winter approaches

• When the Earth is farthest from the sun in its orbit

Winter Solstice

• The longest day of the year in the Northern Hemisphere.

• When one hemisphere experiences its shortest day of the year due to the tilt of Earth away from the sun.

• The day when the sun is directly above the equator.

• The first day of winter in the Southern Hemisphere.

Habitable Zone

• the region around a star in which planets could potentially have surface temperatures at which liquid water could exist

• the area in a galaxy where stars are formed

• the distance from a planet to its star that determines its gravitational pull

• the zone in space where asteroids are most likely to collide

Blueshift

• A Doppler shift in which spectral features are shifted to longer wavelengths, observed when an object is moving away from the observer.

• A Doppler shift in which spectral features are shifted to shorter wavelengths, observed when an object is moving toward the observer.

• A phenomenon where light is emitted at a constant wavelength regardless of the observer's position.

• A shift in sound frequency due to the motion of the source relative to the observer.

Magnetic field

• the region around a magnet where the magnetic force is exerted

• a type of energy that can be harnessed for power

• the area where electric currents are generated

• a phenomenon that occurs only in outer space

Lunar Eclipse

• the blocking of sunlight to the moon that occurs when Earth is directly between the sun and the moon

• the reflection of sunlight off the moon's surface

• the alignment of the sun, Earth, and moon in a straight line

• the scattering of sunlight by the Earth's atmosphere

Dark Energy

• a hypothetical form of energy that influences the universe

• a type of energy used in nuclear reactions

• a form of energy that causes black holes to form

• a renewable energy source from the sun

Astronomical Unit (au)

• the distance between Earth and the sun, about 93 million miles (150 million kilometers)

• the distance between the Earth and the Moon, about 238,855 miles (384,400 kilometers)

• the distance light travels in one year, about 5.88 trillion miles (9.46 trillion kilometers)

• the average distance between Mars and the Sun, about 142 million miles (228 million kilometers)