Quizlet Astronomy 100 Midterm 1 Review PDF

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Quizlet Astronomy 100 Midterm 1 Review...

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Astronomy 100 Midterm 1 Study online at quizlet.com/_3jhcw1 1.

astronomical unit

7.

angular size

Distance between the center of the Earth and the center of the Sun. 2.

light year

the distance light travels in one year; approx. 6 trillion miles

3.

asterism

an unofficial star picture (i.e. "Big Dipper," "Little Dipper"); these aren't the correct names for the constellation but are used colloquially and unofficially

4.

constellation

angle between two sides of a celestial object (also called angular diameter or angular width) 8.

angular separation

angle between two celestial objects

9.

altitude

angle between a celestial object and the horizon

10.

degree

Constellations are of mainly Greek origin; Southern-sky constellations are of 17th century European origin. Sky is divided into 88 official regions. 360 degrees total around the globe

The brightest stars in constellations have names, usually Arabic in origin.

1 degree = 60 arcminutes Greek letters indicate brightness. 5.

11.

arcminute

circumpolar stars

stars that are always above the horizon (i.e. Ursa Major, Ursa Minor, Cassiopeia) 6.

seasonal stars

stars that rise and set (i.e. Orion, Taurus, Canis Major)

finer measurement than a degree 60 arcminutes = 1 degree 1 arcminute = 60 arcseconds

12.

arcsecond

15.

celestial equator

projection of Earth's equator onto the celestial sphere even finer measurement than an arcminute

16.

ecliptic

60 arcseconds = 1 arcminute 13.

celestial sphere

the apparent path of the Sun across the celestial sphere over the course of the year

the imaginary sphere of celestial objects that seems to center on Earth (basically the sky) 14.

Tilted when compared to celestial equator.

north and south celestial poles

Equinox - when the ecliptic crosses the celestial equator Solstice - when the ecliptic is at its highest and lowest points from the celestial equator 17.

projections of Earth's axis onto the celestial sphere

zodiac

the set of constellations through which the ecliptic passes, 13 total according to modern astronomical charts

18.

meridian

22.

equinox

line from North, through the Zenith, to South from horizon to horizon 19.

horizon

20.

zenith

the line at which the earth's surface and the sky appear to meet when the Sun crosses the celestial equator March 20th Equinox September 22th Equinox 23.

latitude

Measured in degrees, 90 degrees from equator to either pole.

the location in the sky directly above you 21.

measure of how far north or south you are from the equator

solstice 24.

longitude

how far east or west you are from the prime meridian Measured in degrees, 180 degrees East and West, converging on the International Date Line. Prime meridian goes through Greenwich, England. Time zones measured East and West from here (Greenwich Mean Time, GMT).

25.

precession

when the Sun is at its highest and lowest points from the celestial equator December 21st Solstice = Lowest point June 21st Solstice = Highest point

the 26,000 year wobble of Earth's axis 26.

waxing

when the moon is getting larger

27.

waning

when the moon is getting smaller

28.

crescent

when less than 50% of the moon is visible, but more than 0%

29.

gibbous

when more than 50% of the moon is visible, but less than 100%

30.

blue moon

when two full moons happen in the same calendar month, the second is called a "blue moon"

37.

eclipse season

Happens every 2.7 years. 31.

blood moon

a total lunar eclipse

32.

supermoon

full moons that occur when the moon is closest to earth in its orbit when the line of nodes points towards the Sun, occurring approximately every six months

The difference in size compared to a regular moon is not easily discernible by the naked eye. 33.

harvest moon

34.

synchronous rotation

Minimum 2 eclipses per eclipse season and 2 eclipse seasons per year. Maximum of 7 eclipses (solar + lunar combined) every year.

full moon that occurs closest to the September equinox

38.

node

the two points where the Moon's orbit crosses the ecliptic

39.

line of nodes

a line that joins the ascending node and the descending node of an orbit In the case of Earth, this line goes straight through the Earth. Probably applies to all other heavenly bodies with satellites, too.

the moon's rotational and orbital periods are equal

40.

umbra

Due to tidal friction (Tidal Locking). 35.

tidal friction

the frictional effect of the tidal wave tending to retard the rotational velocity of the earth and so increase very slowly the length of the day

36.

tidal locking

the situation when an object's orbital period matches its rotational period a full shadow Earth's moon is tidal locked, slowed down in its rotation by the tidal bulge

41.

penumbra

a partial shadow that surrounds the umbra 42.

annular

ring-shaped, in reference to annular solar eclipses, where the Moon is too far away to cover the Sun so a ring of Sun is visible around the Moon

43.

elongation

angle between a planet and the Sun There is a maximum angle of elongation for planets. Mercury has a lower max elongation than Venus because it is closer to the Sun.

44.

retrograde motion

apparent motion of a planet where the planet appears to be moving East to West, then suddenly slows and goes backwards The planets aren't actually reversing motion, it just appears that way due to Earth's orbit around the Sun and the perspective of the other planets from Earth....