Astronomy Midterm #1

Front 1

Definition of a Constellation

Back 1

A pattern of stars that makes a picture

88 official constellations
-Established- 1828 (IAU) international, Astronomical Union
-48 ancient
-40 modern

Front 2

Definition of an Asterism and and example.

Back 2

Locally recognized grouping of stars
Not one of the official 88 constellations

-Big dipper, Summer triangle...

Front 3

Origin and definition of ancient constellations.

Back 3

Important figures from Western cultures around 5,000 yrs ago
(middle east and Mediterranean)

-Northern Hem.
Visible from Seattle

Front 4

Origin and definition of modern constellations.

Back 4

Important figures from 17th century European culture

-Southern Hem.
-Not visible from Seattle

Front 5

Angular measure

Back 5

Angular size/diameter: The size of celestial objects
(often used for (size) of distant star clusters, nebula and galaxies)

Angular separation: (distance) between celestial objects
(used for (distance) of close double stars)

Tells us how much of the sky an object takes up
DOES NOT - tell us how big an object is

*(note)* Both used to locate objects in the sky

Front 6

Angular Degree

Back 6

Degree = is a Measure of angle. A right angle equals 90 degrees.

Front 7

Small Angles:

Degree, Arc min., Arc second.

Back 7

Degree = 1 Arc Min = 60 Arc seconds

Are useful for knowing the separation and/or diameter of objects visible through a telescope

Front 8

Angular measurement using hand: spread out hand, fist, finger.

How do you determine angular size using this method of measurement:

Back 8

FINGER: 1 deg
FIST: 10 deg.
SPREAD HAND: 20 deg.

How to determine angular size: with outstretched hand

Hint 8

*

Front 9

DEFINE:
Altitude
Azmuth

Back 9

Altitude:
Angle in Deg from Horizon to Object in Sky

Azimuth:
Precise way to measure direction. Measured in degree along horizon.

Hint 9

*

Front 10

Polaris (North Star)

Back 10

Polaris:
Located in the sky almost in line with cardinal North. Used to navigate. Not the brightest star in the sky. Can be found using the big dipper.

Hint 10

*

Front 11

DEFINE
Meridian
AM / PM
Horizion

Back 11

MERIDIAN: Divides sky in 1/2 from N horizon, through zenith, and down through S horizon.

Where we get am/pm
AM: Ante meridian (before)
PM: Post meridian (after)


HORIZON: The boundary between the Earth and sky

Hint 11

*

Front 12

DEFINE:
Zenith
Nadir

Back 12

ZENITH: The point directly overhead

NADIR: Point opposite the zenith

Front 13

Cardinal Directions

Back 13

N,S,E,W

Hint 13

*

Front 14

STARS:
Circumpolar & Seasonal

How does Latitude affect which type of star it is?

Back 14

Circumpolar: Never below horizon, Always visible

Seasonal: Visible diff times at night & year

Latitudes affect on type:
What we see in the sky depends on our latitude
@ N.P. Polaris is at zenith. & all constellations seasonal

From Seattle Longitude:
-N Constellations- (ancient) are circumpolar
-S constellations- (modern) are seasonal
-Polaris @ 47.5 deg

Front 15

DEFINE:

Latitude, Longitude

Back 15

LATITUDE:
line goes E/W
Measured north or south of the equator
Equator 0º
N. Pole 90º N
S. Pole 90º S
Seattle 47.5º N

LONGITUDE:
Line goes N/S
Measured east or west of the Prime Meridian in Greenwich England

Hint 15

*

Front 16

DEFINE:

North Pole, equator

Back 16

NORTH POLE:
point in the northern hemisphere where the Earth's axis of rotation meets its surface

EQUATOR: imaginary line on the Earth's surface equidistant from the North Pole and South Pole, dividing the Earth into the Northern Hemisphere and Southern Hemisphere

Hint 16

*

Front 17

DEFINE:
Celestial Sphere
North and South Celestial poles
Celestial Equator

Back 17

CELESTIAL SPHERE:
imaginary sphere of arbitrarily large radius, concentric with the Earth and rotating upon the same axis. All objects in the sky can be thought of as projected upon the celestial sphere. practical tool for positional astronomy.

NORTH & SOUTH CELESTIAL POLES & CELESTIAL EQUATOR:
Projected upward from Earth's equator and poles are the celestial equator and the celestial poles.

Front 18

DEFINE:
Ecliptic
zodiac
Nodes

Back 18

ECLIPTIC:
Yearly path of the sun around the celestial sphere

ZODIAC:
Constellations along the Ecliptic

NODES:
points where the path of the moon on the celestial sphere crosses the ecliptic.

Hint 18

*

Front 19

DEFINE:
Precession & Nutation

Back 19

PRECESSION:
As Earth spins on its axis it Precesses (wobbles) like a top, Axis of tilt remains close to 23.5º from vertical, Wobble causes North Celestial Pole (NCP) to sweep out a circle in the sky

NUTATION: Slight nodding of axis

Hint 19

*

Front 20

DEFINE:
RA (Right Ascension)
DE (Declination)

How and what are these used for in a celestial coordinate system that is similar to Lat. and Long. on earth?

Back 20

RA (Right Ascension):
Measured in Deg. along spring Equinox. (similar to longitude)
East-West distance between spring Equinox and a location on the celestial sphere.

DE (Declination):
Measured in Deg. along celestial EQ. (similar to latitude)
North-South distance between celestial EQ. and a location on the Celestial sphere.

HOW are these used?
RA & DEC Coordinates from star chart entered into a telescope

WHAT are they used for?
Locating faint star with a telescope

Hint 20

*

Front 21

DEFINE:
Annual Motion
Revolve
Daily Motion
Rotate

Back 21

ANNUAL MOTION:
Earth Revolves around Sun 1 time per Year., Different constellations are seen at different times of year

REVOLVE:
Motion of body around another body

DAILY (diurnal) MOTION: The Sun, Moon, planets and stars appear to move across the sky. Westward direction

ROTATE:
Spinning of object around its axis

Hint 21

*

Front 22

DEFINE:

Solar Day
Sidereal Day

Back 22

SOLAR DAY:
24 hrs. average time between suns appearances on the meridian.

SIDEREAL DAY:
Essentially the true rotation period of the Earth
23 hrs & 56 min. , 4.9 sec. between successive appearances of any star on the meridian;

Hint 22

*

Front 23

DEFINE:

Seasons
solstice
equinox

Back 23

-----SEASONS:
Spring, Summer, Fall, Winter
-----SOLSTICE:
--sun is at its greatest distance from the celestial equator
--Summer solstice June 21st (Longest day of year)
--sun is in zenith of the tropic of Cancer
--Winter solstice Dec 21st (Shortest day of the year)
Sun is in zenith of tropic of Capricorn
---EQUINOX: two points on the celestial sphere at which the ecliptic intersects the celestial equator

Front 24

SIGNIFICANCE, DEFINITION & SEASONS In

Tropic of Cancer (North Hem.)

Back 24

TROPIC OF CANCER (NORTH)
--Latitude 23.5 deg N, Northern most Lat at which the sun ever passes directly overhead
---SIGNIFICANCE:
-Tropics have great significance to the seasons due to the suns location/high vs low angle and time in the sky.
-Sun is directly over head at noon, (during summer solstice) -Longest day of the year (in northern hem)
---SEASONS: Summer
-----*note* (Seasons in north and south hemispheres are opposite)

Front 25

SIGNIFICANCE, DEFINITION of & SEASONS In;

Tropic of Capricorn (S)

Back 25

TROPIC OF CAPRICORN (s):
--(The circle on the earth with latitude 23.5 S, which marks the southern most latitude at which the sun ever passes directly overhead (which it does at noon on the winter solstice)
--SIGNIFICANCE: The suns angle is more extreme in the Southern Hem and less extreme in the Northern Hem.
--SEASONS: In the northern Hem the season is winter when sun is in this position.
----*note* (Seasons in north and south hemispheres are opposite)

Front 26

DEFINITION of & SEASONS In;

ARCTIC CIRCLE

Back 26

ARCTIC CIRCLE: Just below the NP the circle on the earth with Latitude of 66.5

SEASONS: June solstice Sun never sets, December solstice sun never rises.

Hint 26

*

Front 27

SEATTLE: Seasons, pattern of sun movement,

Back 27

-----SEATTLE SEASONS-
SUMMER: June 21st, axis from N is pointed toward sun
WINTER: Dec. 21st, axis from N is pointed away from sun
SPRING: March 21st, N&S axis equal distance away from sun
FALL: Sep: 21st, N&S axis equal distance away from sun
-----PATTERN OF SUN MOVEMENT: (sun in each equinox) Position of sunrise & sunset changes everyday, repeats every year.
--SPRING: sun up 12hr, sun down 12hr, sun med. height at noon, Sunrise E, Sunset W.
--FALL: sun up 12hr , sun down 12hr, sun med. height at noon, Rises: E Sets: W
--SUMMER: sun up 15hrs, down 9hrs, Highest sun ever gets at noon, Rises: NE, Sets: NW
--WINTER: sun up 9hrs, down 15hrs, Lowest sun ever gets at noon, Rises: SE Sets: SW

Front 28

When is the earth closest and farthest from the sun?

How important is this to seasons?

Back 28

FARTHEST: Summer (July 4th)

CLOSEST: Winter

IMPORTANCE TO SEASONS: None. (More important is the angle of the earth to the sun and how high/long the sun is in the sky.)

Hint 28

*

Front 29

MOON PHASES:
Waxing, Waning, Crescent, Gibbous, Full, New

*(note) each phase takes aprox. 1/2 week (3-4days), each quarter takes 1 full week

Back 29

---WAXING: (Lit on the right side) more of the visible face of the moon is becoming illuminated, the phases that come after the new moon but before full moon
---WANING: (Lit on the Left side) Set of phases which less of the visible face of the moon is illuminated. (phases that come after full moon, before new moon)
---CRESCENT: Sliver of moon illuminated, Can be in either waxing or waning phase.
---GIBBOUS: Majority of moon lit, can be either wax. or wan.
---FULL: (2 weeks from new moon) visible side of moon completely illuminated
---NEW: (4 weeks from previous new moon) visible side of moon completely dark.

Front 30

THE MOON:
Synodic period, Sideral period, Month.

Back 30

---LUNA: Means moon
---SYNODIC PERIOD:
Complete cycle of lunar phases
Aprox. 30days, 4wks, 1month
(time it takes for the object to return to the same position with respect to the Sun)
---SIDERAL PERIOD: True orbital period of the moon, 27days
(time it takes to return to the same position with respect to the stars)
---MONTH: lunar month: The average time between successive new or full moons, equal to 29 days 12 hours 44 minutes. Also called synodic month.

Front 31

ECLIPSES:
Lunar Eclipse, Solar Eclipse, Eclipse Season,

Back 31

LUNAR ECLIPSE: Occurs when earth lies directly between sun and moon, Earth's shadow falls on moon.

SOLAR ECLIPSE: Occurs when moon lies directly between the sun and Earth, moon's shadow falls on Earth. (People living within the area covered by the moons shadow will see the sun blocked or partially blocked from view)

ECLIPSE SEASON: 2 Times of the year when the Moon lies in the same plane as the Earth and Sun, so that eclipses are possible.

Hint 31

*

Front 32

ECLIPSES:
Node, Umbra, Penumbra, Eclipse Path;

Back 32

--NODE: Two points in each orbit at which the moon crosses the surface. (Full & New moons)
--UMBRA: (full shadow) where sun is completely blocked
--PENUMBRA: (Partial shadow) where light is only partially blocked
--ECLIPSE PATH: In order to view a solar eclipse you need to be within its path on earth.

Front 33

PLANETARY MOTION:
Retrograde, Prograde (direct) motion, Elongation, Transit

Back 33

--RETROGRADE MOTION: ("backward" West) appear to reverse from normal eastward motion to westward
--PROGRADE (direct) MOTION: Normal and usual eastward motion against the stars
--ELONGATION: The configuration between two celestial bodies can be described using the angle between them (measured along the ecliptic), which is called their elongation
--TRANSIT: the astronomical event that occurs when one celestial body appears to move across the face of another celestial body, hiding a small part of it, as seen by an observer at some particular vantage point.

Front 34

How do you predict the approx. rise and set time for different moon phases?

Back 34

*The most relevant factor in determining the times of moonrise and moonset is the phase of the moon.

EXAMPLE:
new moon
moon rise06:00 AM
moon set 06:00 PM

young crescent
Moon rise 09:00 AM
Moon set 09:00 PM

Front 35

Which is longer?

Synodic period or the Siderial period?

Synodic day or Siderial day?

Back 35

--Synodic period and the synodic day are both longer than Sideral.

LONGER: The SYNODIC period is longer at
Complete cycle of lunar phases, Aprox. 30days, 4wks, 1month

SIDERAL PERIOD:
True orbital period of the moon, 27days, Measured according to the stars

LONGER: Synodic day: rotate once in relation to the body it is orbiting, 24 hours

Syderial day: (one complete rotation in relation to the stars).
23 hours 56 minutes and 4.09 seconds

Front 36

History 1:
Geocentric, Heliocentric, Epicycle, Deferent.

Back 36

GEOCENTRIC: Earth centered universe

HELIOCENTRIC: Sun centered universe

EPICYCLE: planets had their own small Circles upon their revolution (DEFERENT) circles, attempt to predict retrograde with a geocentric model.

DIFERENT: The large circle upon which a planet follows its circle upon circle path around the earth in a Geocentric (Ptolemaic) model of the universe.

Hint 36

*

Front 37

LUNAR ECLIPSE:
Partial, Total, penumbral

Back 37

PARTIAL: only part of the full moon passes through earths umbra

TOTAL: if the sun, earth and full moon are nearly perfectly aligned, the moon passes through the earths umbra and we see total lunar eclipse

PRENUMBRAL: If the moon only passes through the earths prenumbra (partial shadow / partial blockage of sunlight)
-These are the most common lunar eclipses, but least impressive, darkening the moon only slightly.

Hint 37

*

Front 38

SOLAR ECLIPSE:
Partial, Total, Annular

Back 38

PARTIAL solar eclipse: Part of the sun is blocked from view.

TOTAL solar eclipse: The Moon blocks the full disk of the sun, only if you are within the umbra; totality lasts no more than a few minuets, because of the Earths rotation and moon's orbit.

ANNULAR solar eclipse: Ring of sunlight surrounds disk of moon

Hint 38

*

Front 39

Why don't we have solar eclipses every month?

Back 39

the Moon's orbit is inclined about 5 degrees to the Earth's orbit. The Moon passes through the ecliptic only twice a month at a pair of points called the nodes. The rest of the time the Moon is either above or below the plane of the Earth's orbit and does not pass directly through the Earth's shadow.

Hint 39

*

Front 40

Where do you have to be to see a solar eclipse?

Back 40

In order to see a solar eclipse you need to be within the ECLIPSE PATH.

Hint 40

*

Front 41

Why is it more common to see a total Lunar eclipse than a total Solar eclipse even though the occur with about the same regularity?

Back 41

A lunar eclipse happens on the Moon, and is visible from half of the Earth at once. A solar eclipse is only visible at the point of the Moon's shadow on the Earth, and 75% of the Earth's surface is water.

Hint 41

*

Front 42

what is Milankovich Hypothesis and how does it affect climate?

Back 42

Milankovich Hypothesis

-suggests that the slight changes in the earth's shape, orbits, precession etc. affect the climate and trigger ice ages.

Hint 42

*

Front 43

How many planets are visible to the unaided eye?

Back 43

5 planets are visible with unaided eye

-Mercury,Venus, Mars, Jupiter, Saturn

Front 44

How do you tell a planet from a star?

Back 44

1. Brighter, 2. Different colors, 3. Don't twinkle , 4. found along ecliptic, 5. planets move "wandering star"

Front 45

What did Ptolemy contribute?

Back 45

Ptolemy Contributed:

Ptolemaic model:
(Each planet moved upon its own epicycle circle while revolving around earth.)

attempt to explain planetary motion.

Hint 45

*

Front 46

What did Copernicus contribute?

Back 46

Copernicus contributed:

Heliocentric model of the universe (Sun @ center)
-constant speeds, perfect circles
-Earth moved around sun faster than outer planets

Hint 46

*

Front 47

What did Galileo Contribute?

Back 47

First to look into the sky with telescope
DISCOVERED
-moon had mountain's and valleys, Jupiter had 4 moons, proved Earth was not center, Venus went through all phases - contrary to geocentric model, Saturn had "cup handles" or "Ears", Sun had dark spots that moved, proving suns rotation, Milky way made of a myriad of stars

Front 48

What is the difference between astrology and astronomy?

Back 48

ASTROLOGY: Pseudo belief system based on birthdate and what constellation the sun was in when you were born.

ASTRONOMY: Proven science, Observations of stellar bodies in Space

Hint 48

*

Front 49

How many signs are in the Zodiac?

Have the signs shifted from the dates accepted by astrologers?

Back 49

- There are 13 signs in the Zodiac. The 13th is Ophiuchus.

-Yes the signs have shifted. The dates are approx 2,000 yrs out of date.