EDUC 224-Earth & the Universe

moons

satellites which orbit planets (ex: phobos)

lunar cycle / phase of the moon

the appearance of the surface of the moon as seen on earth (ex: full moon)

electromagnetic force

interactions (pushes and pulls) of electrically charged particles with other charged particles and magnetic poles (ex: like charges repel, opposite charges attract)

asteroids

small, rocky bodies in the sun’s orbit (ex: ceres)

pulsar

a rapidly rotating neutron star; emits pulsing radio waves (ex: Vela Pulsar)

time zones

a region of the earth which observes a uniform standard time; there are around 37 time zones, depending on daylight saving time (ex: Nepal Standard Time)

nebula

a gas and dust cloud in space (ex: Orion Nebula)

neptune

the eighth planet from the sun; an outer planet (outside the asteroid belt); methane in the atmosphere absorbs red light to make it appear blue; gives off over twice as much energy as it receives from the sun

plasma

a state of matter in which atoms have been stripped of their electrons; electrons move freely around a plasma (ex: inside the sun)

mars

the fourth planet from the sun; an inner planet (inside the asteroid belt); the “Red Planet”; home to Olympus Mons, the tallest mountain in the solar system

dwarf planet

a small planet not large enough to clear its orbit of debris (ex: pluto)

exoplanets

planets which orbit stars outside our own solar system (ex: Proxima Centauri b)

pluto

previously classified as the ninth planet from the sun; usually now classified as a minor planet or dwarf planet; has five moons

winter

coldest season; begins with the shortest daylight hours (winter solstice) and ends with equal daytime and nighttime hours (spring equinox)

nuclear fission

a process in which the nuclei of light elements, like hydrogen, fuse together to create the nuclei of heavier elements, like helium (ex: reactions within the sun)

saturn

the sixth planet from the sun; an outer planet (outside the asteroid belt); the least dense planet; has a complex ring system

irregular galaxy

a star system without a defined shape (ex: Large Magellanic Cloud)

virgo supercluster

a supercluster of galaxies that contains the Local Group and spans over 100 million light-years

autumnal equinox

a day all latitudes have equal day and night, marking the beginning of fall; occurs around September 23 in the northern hemisphere and around March 21 in the southern hemisphere

luminosity

the amount of energy emitted by a light source each second (Watts)

local group

a group of galaxies that contains the Milky Way galaxy and spans almost 10 million light-years

meteorite

what remains of a meteor after it hits the surface of the earth

neutron star

a small star with high density; made of closely packed neutrons (ex: Crab Pulsar)

makemake

a dwarf planet in the Kuiper belt

solar wind

the stream of charged particles that flows from the Sun throughout the solar system

andromeda galaxy

the nearest major galaxy to the Milky Way

meteorological seasons

groupings of three months based on common climate conditions; meteorological seasons start at the beginning of the months that contain solstices or equinoxes

sunspot

an area of the Sun’s photosphere that looks dark because it is cooler than the surrounding solar material

waxing gibbous

the phase during which the illuminated side of the moon is increasing, and more than half the face of the moon is illuminated as seen from Earth

absorption spectrum

a series of black lines in a continuous spectrum that occur when atoms absorb light energy

red supergiants

stars with high luminosity, low surface temperature, and a minimum mass of 15 times the mass of the Sun (ex: Betelgeuse)

minor planets

synonym for planetoid, also includes large asteroids

spiral galaxy

a relatively flat, disk-shaped star system with one or more arms that spirals out from the central “bulge” of stars (ex: Milky Way and Andromeda Galaxies)

solar eclipse

an event in which the sun’s surface is obscured or darkened by the moon

milky way galaxy

the spiral galaxy in which our solar system is located

comet

a body made of ice and dust in the sun’s orbit; contains a gas and dust “tail” (ex: Halley’s Comet)

haumea

a dwarf planet with an orbit beyond neptune

jupiter

the fifth planet from the sun; an outer planet (outside the asteroid belt); largest planet; over twice as massive as all the other planets combined; has four large moons; about 90% hydrogen and 10% helium

uranus

the seventh planet from the sun; an outer planet (outside the asteroid belt); composed mostly of rock and ice; has 27 named moons

binary stars

a two-star system; the stars rotate around a common point, or one star rotates around the other (ex: castor)

normal spiral galaxy

a spiral galaxy with arms that extend from a nuclear region or bulge (ex: Andromeda Galaxy)

galaxy

a system of stars, gas, and dust held together by gravity

earth’s tilt

earth is tilted 23.5 degrees, which causes Earth’s seasons

celestial bodies

a physical object in space which has observable characteristics (ex: planet)

new moon

the phase during which the moon starts the cycle around the Earth. the moon is between the Sun and the Earth. to observers on the Earth, it appears to be unlit

black hole

an object with gravity great enough that it does not allow radiation or matter to escape

eris

the most massive and second largest dwarf planet in the solar system

lenticular galaxy

a cross between spiral and elliptical galaxies; disc-shaped with a central bulge

waxing crescent

the phase during which the illuminated side of the moon is increasing, but less than half the face of the moon is illuminated as seen from Earth

corona

the outer atmosphere of the Sun

spring equinox

a day all latitudes have equal day and night, marking the beginning of the transition from winter to summer; occurs around March 21 in the northern hemisphere and September 23 in the southern hemisphere

constellations

a star grouping which forms a patters; we have ascribed images to the constellations (ex: Orion)

protostars

the earliest stage of star formation where a nebula begins to collapse due to its own gravity

apparent magnitude

how bright a star looks to an observer on Earth

planetary nebula

a cloud of gas and dust that surrounds a white dwarf; does not contain materials able to form planets, despite the name

photosphere

the opaque, innermost visible layer of the Sun that surrounds the convective zone

daylight saving time

the practice of setting clocks forward one hour during the summer months

asteroid belt

the region of space between Mars and Jupiter containing most of the solar system’s asteroids

northern hemisphere

the half of the earth north of the equator

ceres

a dwarf planet located in the asteroid belt between Mars and Jupiter

quasar

an extremely bright galactic nucleus in the center of a very old, very distant galaxy, thought to be powered by a black hole at its center

december solstice

the day of the shortest daylight of the year in the northern hemisphere (winter solstice) and the longest daylight of the year in the southern hemisphere (summer solstice); occurs around December 22

absolute magnitude

the actual amount of light a star gives off (ex: the absolute magnitude of the Sun is 4.8)

astronomical seasons

seasons beginning on the date of each solstice or equinox; astronomical summer starts on the summer solstice around June 21

friction

the force, in the opposite direction of motion, between two objects moving over one another

redshift

a shift in the light from a star toward the red end of the visible spectrum that is produced when the star is moving away from the Earth

spring

transition season between winter and summer that begins with equal daytime and nighttime hours (spring equinox) and ends with the longest daylight hours (summer solstice)

chromosphere

the red-colored layer of the Sun that is on the outside of the photosphere

shooting star

a streak of light in the night sky caused as a meteor burns up in the atmosphere

elliptical galaxy

a star system that is relatively smooth, and elliptical or oblong in shape; more three dimensional and less flat than a spiral galaxy (ex: M60 Galaxy)

singularity

an infinitely small, dense center of a black hole

main sequence stars

stars that fuse hydrogen into helium; most stars spend most of their lives in this stage

gravitational force

the force of attraction of all masses toward each other due to gravitational pull (ex: Earth pulls on Moon)

white dwarf

a small star with high density; often the size of a planet (ex: Sirius B)

supernova

explosion of a high-mass star that blows off the outer layers and condenses the core

red giants

large stars with a high luminosity and low surface temperature

convection

the transfer of heat by a moving fluid, like air and water (ex: heat rising from a lit candle)

big bang

a sudden expansion of the Universe that produced an explosive growth in the size of the entire Universe the continues today

fall (autumn)

transition season between summer and winter that begins with equal daytime and nighttime hours (fall equinox) and ends with the shortest daylight hours (winter solstice)

doppler effect

an increase in the frequency of a wave when an emitter and/or an observer move toward each other and a decrease in the frequency when the objects move apart (ex: police radar)

parsec

a unit of length to measure large distances ; equivalent to 3.26 light-years

stars

a gaseous body which produces radiant energy through nuclear fusion reactions (ex: the sun ; Sirius)

revolve

when a planet moves about another object; Earth revolves around the Sun, and the moon revolves around Earth

summer

warmest season; begins with the longest daylight hours (summer solstice) and ends with equal daytime and nighttime hours (fall equinox)

oort cloud

a shell of comet bodies which orbit the sun

hertzsprung-russell diagram

a diagram that charts stars by their temperature, luminosity (brightness), spectral class, and absolute magnitude

solar flare

a burst of high-energy radiation from the Sun’s surface that is associated with sunspots

spectroscope

an instrument that splits lights into separate wavelengths; can be used to determine the composition of a star

vernal equinox

a day all latitudes have equal day and night, marking the beginning of spring; occurs around March 21 in the northern hemisphere and around September 23 in the southern hemisphere

period (of a comet)

the amount of time it takes for a comet to orbit the sun (ex: Halley’s Comet has a period of about 75 years)

gyrochronology

a technique used by astronomers that uses a star’s rotation rate and color to determine its age

mercury

the first planet from the sun; an inner planet (inside the asteroid belt); slightly larger than Earth’s moon; experiences extreme temperature variations; large iron core

meteor

a meteoroid that has entered Earth’s atmosphere

galaxies

a system of stars and their systems held together by gravity (ex: Milky Way Galaxy)

frequency

the number of occurrences of an observed behavior over a set time period (ex: a teacher counting the number of times Jacob sticks his tongue out at a classmate during a one hour class would be collecting frequency data)

emission spectrum

a series of colored lines of different wavelengths (or frequencies) produced when electrons in atoms fall from higher to lower energy levels

blueshift

a shift in the light from a star toward the blue end of the visible spectrum that is produced when the star is moving towards Earth

summer solstice

the day of longest daylight; occurs around June 21 in the northern hemisphere and December 22 in the southern hemisphere

fall equinox

a day all latitudes have equal day and night, marking the beginning of the transition from summer to winter; occurs around September 23 in the northern hemisphere and around March 21 in the southern hemisphere

solar system

a star, as well as the planets, satellites, asteroids, and all the other objects orbiting it, travelling together through space