Astronomy

Time Zones (37 depending on DST)

Region of earth which observes uniform standard time

Daylight Saving Time

Practice of setting clocks forward one hour during summer months

Revolve

When planet moves about another object

Earth’s Tilt

23.5 degrees, causes earth’s seasons

Astronomical Seasons

Seasons beginning on date of each solstice or equinox

Summer/June Solstice

Day of longest daylight occurring around June 21 in NH and December 22 in SH

Autumnal/September Equinox

All latitudes have equal day and night occurring around September 23 in NH and March 21 in SH

Winter/December Solstice

Day of shortest daylight occurring around December 22 in NH and June 21 in SH

Vernal/March Equinox

All latitudes have equal day and night occurring around March 21 in NH and September 23 in SH

Meteorological Seasons

Groupings of 3 months based on common climate conditions starting at beginning of months that contain solstices or equinoxes

Winter

Coldest season beginning w/ shortest daylight hours and ends w/ equal daytime and nighttime hours

Spring

Transition season btwn winter and summer that begins w/ equal daytime and nighttime hours and ends w/ longest daylight hours

Summer

Warmest season beginning w/ longest daylight hours and ends w/ equal daytime and nighttime hours

Fall

Transition season btwn summer and winter beginning w/ equal daytime and nighttime hours and ends w/ shortest daylight hours

Lunar Cycle/Moon Phase

Appearance of surface of moon as seen on earth

New Moon

Phase during which moon starts cycle around earth located btwn sun and earth appearing unlit

Waxing Crescent

Phase during which illuminated side of moon is increasing but less than half of moon is illuminated

First Quarter

Phase during which moon traveled ¼ of way around earth appearing half illuminated

Waxing Gibbous

Phase during which illuminated side of moon is increasing and more than half of the moon is illuminated

Full Moon

Phase during which moon traveled halfway around earth appearing fully illuminated

Waning Gibbous

Phase during which illuminated side of moon is decreasing but more than half of moon is illuminated

Third Quarter

Phase during which moon traveled ¾ of way around earth appearing half-illuminated

Waning Crescent

Phase during which illuminated portion of moon is decreasing and less than half moon’s face is illuminated

Lunar Eclipse

Event in which moon’s surface is obscured or darkened by earth’s shadow

Solar Eclipse

Event in which sun’s surface is obscured or darkened by moon

Solar System

Star, planets, satellites, asteroids, and all other objects orbiting it travelling together through space

Dwarf Planet

Small planet not large enough to clear its orbit of debris

Satellite

Object/body that orbits another object/body

Asteroids

Small rocky bodies in sun’s orbit

Meteoroids

Small bodies of debris from space which move into earth’s atmosphere and turn into meteors

Meteor

Meteoroid that entered earth’s atmosphere

Shooting Star

Streak of light in night sky caused as meteor burns up in atmosphere

Meteorite

What remains of meteor after it hits surface of earth

Comet

Body made of ice and dust in sun’s orbit containing gas and dust tail

Period

Amount of time for comet to orbit sun

Small Solar System Bodies (SSSBs)

All small bodies in solar system except planets, dwarf planets, and satellites

Planetoids

Bodies that orbit sun smaller than planets and larger than asteroids

Minor Planets

Synonym for planetoid also includes large asteroids

Planet

Body moving in orbit around star large enough to clear debris in its orbit and has enough gravity to make it round

Asteroid Belt

Region of space btwn Mars and Jupiter containing most of solar system’s asteroids

Mercury

1st planet from sun, inner planet, slightly larger than earth’s moon, experiences extreme temp variations, large iron core

Venus

2nd planet from sun, inner planet, slightly smaller than earth, similar density and chemical composition to earth

Earth

3rd planet from sun, inner planet, only known habitable planet, 71% of surface covered w/ liquid water

Mars

4th planet from sun, inner planet, “red planet”, home to Olympus Mons tallest mountain in solar system

Jupiter

5th planet from sun, outer planet, largest planet, over 2x as massive as all other planets combined, 4 large moons, 90% hydrogen and 10% helium

Saturn

6th planet from sun, outer planet, least dense planet, complex ring system

Uranus

7th planet from sun, outer planet, composed mostly of rock and ice, 27 named moons

Neptune

8th planet from sun, outer planet, methane in atmosphere absorbs red light to make it appear blue, gives off over 2x as much energy as it receives from sun

Kuiper Belt

Flat disc of comets, asteroids, and other small icy objects that orbit sun at distance beyond Neptune

Ceres

Dwarf planet located in asteroid belt btwn Mars and Jupiter

Pluto

Previously classified as 9th planet from sun usually now classified as minor/dwarf planet w/ 5 moons

Haumea

Dwarf planet w/ orbit beyond Neptune

Makemake

Dwarf planet in Kuiper Belt

Eris

Most massive and second largest dwarf planet in solar system

Celestial Bodies

Physical object in space which has observable characteristics

Milky Way Galaxy

Spiral galaxy in which our solar system is located

Virgo Supercluster

Supercluster of galaxies that contains Local Group and spans over 100 million lightyears

Local Group

Group of galaxies that contains Milky Way galaxy and spans almost 10 million lightyears

Oort Cloud

Shell of comet bodies which orbit sun

Moons

Satellites which orbit planets

Exoplanets

Planets which orbit stars outside our own solar system

Stars

Gaseous body which produces radiant energy through nuclear fusion reactions

Binary Stars

2-star system where stars rotate around common point or one star rotates around other

Constellation

Star grouping which forms pattern

Black Holes

Object w/ gravity great enough that it does not allow radiation or matter to escape

Nebula

Gas and dust cloud in space

Galaxies

System of stars and their systems held together by gravity

Luminosity

Amount of energy emitted by light source each second (watts)

Absolute Magnitude

Actual amount of light star gives off

Parsec

Unit of length to measure large distances equivalent to 3.26 lightyears

Apparent Magnitude

How bright star looks to observer on earth

Hertzsprung-Russell (H-R) Diagram

Diagram that charts stars by temp, luminosity, spectral class, and absolute magnitude

Red Giants

Large stars w/ high luminosity and low surface temp

White Dwarf

Small star w/ high density often size of planet

Neutron Star

Small star w/ high density made of closely packed neutrons

Main Sequence Stars

Stage most stars spend most of their lives in fusing hydrogen into helium

Red Supergiants

Stars w/ high luminosity, low surface temp, and min mass of 15x mass of sun

Blue Giants

Large stars w/ high luminosity and high surface temp

Pulsar

Rapidly rotating neutron star that emits pulsing radio waves

Singularity

Infinitely small dense center of black hole

Spectroscope

Instrument that splits light into separate wavelengths used to determine composition of star

Emission Spectrum

Series of colored lines of different wavelengths produced when electrons in atoms fall from higher to lower energy levels

Absorption Spectrum

Series of black lines in continuous spectrum occurring when atoms absorb light energy

Doppler Effect

Helps determine rate celestial objects spin and whether they’re moving towards or away from earth

Blueshift

Shift in light from star toward blue end of visible spectrum produced when star moves toward earth

Redshift

Shift in light from star toward red end of visible spectrum produced when star moves away from earth

Gyrochronology

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

Nuclear Fusion

Process in which nuclei of light elements fuse together to create nuclei of heavier elements

Protostar

Earliest stage of star formation where nebula begins to collapse due to its own gravity

Planetary Nebula

Cloud of gas and dust surrounding white dwarf that does not contain materials able to form planets

Supernova

Explosion of high mass star that blows off outer layers and condenses core

Big Bang

Sudden expansion of universe that produced explosive growth in size of entire universe that continues today

Quasar

Extremely bright galactic nucleus in center of very old very distant galaxy thought to be powered by black hole at its center

Lenticular Galaxy

Cross btwn spiral and elliptical galaxies that are disc-shaped w/ central bulge

Spiral Galaxy

Relatively flat disk-shaped star system w/ 1+ arms that spirals out from central bulge of stars

Halo

Region around spiral galaxy containing clusters of old stars

Normal Spiral Galaxy

Spiral galaxy w/ arms that extend from nuclear region or bulge

Barred Spiral Galaxy

Spiral galaxy w/ bar of material in central region, arms extend from bar

Andromeda Galaxy

Nearest major galaxy to Milky Way

Elliptical Galaxy

Star system relatively smooth and elliptical or oblong in shape more 3d and less flat than spiral galaxy