Transcript Ecliptic Galactic Equatorial B1950 Equatorial J2000

Celestial Coordinate Systems
K-12 Coordinate Curriculum
Karen Lancour
Chandra Resource Agent
and
Mark Van Hecke
Chandra Resource Agent
Night Sky
• Sky appears as inside
of a very large sphere
• 88 constellations
• Important to specify
positions of objects in
the sky in relation to
one another
• Coordinate systems
Appearance of the Night Sky
• 3-dimensional space
appears as a 2dimensional flat
surface
• Like a photograph or
drawing
• Different methods
are used to
determine distance
from earth
Spherical Coordinates
• Geographic &
Celestial systems are
spherical coordinate
systems
• 2-dimensional
systems
• Fundamental Plane –
Equator
• Polar Axis
• North & South Poles
Celestial Sphere
• Huge, hollow,
imaginary sphere
• Infinite radius
• Appears to rotate east
to west
• Earth is actually
rotating west to east
• Celestial Equator
• North Celestial Pole
and South Celestial
Pole
Coordinate Systems – Different
Reference Planes
• Major Coordinates
Systems
• Different reference
planes for Celestial
Sphere
• North-South Axis
perpendicular to
reference plane
• Developed to facilitate
different perspectives
Coordinates – Angular Measurements
• Angular
measurements
• Latitude-like
coordinates
• Longitude-like
coordinates
• Zero point of
longitude
• Local meridian
Latitude and Longitude
• Circles of latitude
• Same latitude
• Meridians of
longitude
• Same longitude
• Zero point or prime
meridian
Geographic System
• Equator is 0 degrees
• North Pole is 90
degrees N.
• South Pole is 90
degrees S.
• Greenwich meridian
• 0 to 180 degrees east
• 0 to 180 degrees west
Geographic Coordinates
• 360 degrees of arc in
a circle
• Each degree has 60
minutes of arc
• Each minute of arc
has 60 seconds of arc
Geographic and Celestial Coordinate Systems
Spherical
Coordinate
System
Geographic
Latitude Longitude
Horizon
Alt-AZ
Local Equatorial
HA – Dec
Equatorial
RA-Dec
Ecliptic
Longitude-Latitude
Galactic
Longitude-Latitude
Earth – Local
Sky
Sky
Sky
Astronomical
Horizon
Celestial Equator
Celestial Equator
Ecliptic
Galactic Plane
North and South
Earth Poles
Zenith, Nadir
North and South
Celestial Poles
North and South
Celestial Poles
North and South
Ecliptic Poles
North and South
Galactic Poles
Latitude-Like
Coordinates
N is + 90
S is – 90 
Latitude (L, lat)
Altitude (Alt)
Latitude of
Observer
0 to + 90
Declination (Dec)
Declination (Dec)
Ecliptic Latitude (Lat)
Galactic Latitude (B)
LongitudeLike
Coordinates
360
Longitude (long)
0 to 180 E and
0 to 180 W
Azimuth (AZ)
N=0, E=90
S=180, W=270
Clockwise - LH
(E to W)
Hour Angle
(HA)
0 – 24 Hrs.
Clockwise - LH
(E to W)
Right Ascension
(RA)
0 to 24 hr or
0 to 360
CounterclockwiseRH (W to E)
Ecliptic Longitude
(Lon)
0 to 360
CounterclockwiseRH
(W to E)
Galactic Longitude
(L)
0 to 360
Counterclockwise-RH
(W to E)
Longitude
(Zero Point)
Prime Meridian
North Point of
Horizon
Celestial
Meridian
Zero-Point
Affixed to Earth
Vernal Equinox
Zero-Point Affixed
to Sky
Vernal Equinox
Galactic Center
Physical Basis
Circumference
of the Earth
Direction of
Gravity
Earth’s Rotation
Earth’s Rotation
Earth’s Orbital
Motion
Galactic Plane
Used For:
Determining
Geographic
Location
Personal
Observation and
Some telescopes
Setting of
Telescopes
To Track Objects
Cataloging
Positions and to
Determine
Locations
Solar System
Structure
Milky Way and Other
Galactic Structures
Earth vs. Sky
Based System
Earth
Great Circle of
Fundamental
Plane
( x-y plane)
Equator
Polar Axis
(z axis)
0 to 90N
0 to 90S
Earth - Local
0 to +90 (N)
0 to – 90 (S)
0 to + 90 (N)
0 to – 90 (S)
0 to +90 (N)
0 to – 90 (S)
0 to +90 (N)
0 to – 90 (S)
Horizon System
• For Personal
Observation
• Plane of local horizon
• Zenith – 90 degrees
above horizon
• Nadir – 90 degrees
below horizon
• Horizon affected by
the latitude of the
observer.
Horizon System - Alt-AZ
• Altitude – angle of
object above the
horizon
• Azimuth – angle of
object around the
horizon clockwise
from north
Horizon System - Alt-az
• Altitude = 0 to 90 deg
• Azimuth = 0 to 360
deg
• North point defined
• North = 0 deg
• East = 90 deg
• South = 180 deg
• West = 270 deg
Horizon System
• Observer’s view
• Geography
dependent
• Altitude of NCP =
latitude of observer.
• Time and Season
dependent
• Same object has
different coordinates
at different times
Local Horizon – North Pole
• View from North Pole
• Zenith is North
Celestial Pole
• Local horizon is
parallel to Celestial
Equator
• Stars rotate parallel to
horizon (celestial
equator)
• Stars never rise and
set
Local Horizon – Fairbanks
• View from Fairbanks
• Altitude of NCP
equals latitude of
observer.
• Stars move parallel to
the celestial equator
• As one moves south,
the NCP moves away
from zenith toward
the north point of
horizon
Local Horizon - Seattle
• View from Seattle
• Stars rise in east and
set in west
• NCP moves further
away from Zenith
• Arc of star movement
above horizon gets
steeper
Local Horizon – Los Angeles
• View from Los
Angeles
• 34 deg latitude
• NCP at 34 deg above
the horizon and 56
deg from zenith
• All observers on 34th
parallel see the same
star path
• Star path is steeper
Local Horizon – Equator
• View from equator
• NCP is parallel to
local horizon
• Celestial Equator is
perpendicular to local
horizon
• Zenith is on celestial
equator
• Stars rise and set
perpendicular to
horizon
Local Equatorial System
• Stars rise in east and set
in west
• Motion of each star =
parallel of declination on
the Celestial Sphere
• Celestial Equator is half
way between NCP and
SCP
• Related to sidereal “star”
time
• Used to track motion of
stars
Local Equatorial System “HA-dec”
• Used to track objects
• Latitude (Declination)
is from the Celestial
Sphere
• Longitude uses Hour
Angle
• Follows star path from
east to west
• Is still time dependent
at local meridian
Hour Angle
• Time before and after star reaches zenith of its
path
Equatorial System “RA-dec”
• Used to catalog
objects
• Celestial Sphere
• Celestial Equator
• NCP and SCP
• Declination (latitude)
• Right Ascension
(longitude)
• Vernal Equinox
Declination
• Angle above Celestial
Equator
• Parallels of
Declination
• CE = 0 deg
• NCP = 90 deg
• SCP = - 90 deg
Right Ascension
• Hour circles or
“meridians”
• Equator = 360 arc
deg circumference
• Measured as hours
(24 hours)
• 1 hr = 15 arc degrees
• Counterclockwise
• 0h = vernal equinox
Ecliptic
From Earth,
1. Sun ‘s apparent path
2. Inclined 23.5 deg to
Celestial Equator
3. Vernal Equinox
4. Autumnal equinox
5. Winter Solstice
6. Summer Solstice
Ecliptic System
• Earth revolves around
sun = ecliptic
• Ecliptic is
fundamental plane
• Axis of rotation
• North Ecliptic Pole
• South Ecliptic Pole
• Planets have similar
paths around sun
Ecliptic System & Planets
• Used to study solar
system
• Except for Pluto at 17
degrees
• Orbital Inclination
within 7 degrees of
Ecliptic
Planet
Orbital Inclination
Mercury
7.00°
Venus
3.39°
Earth
0.00°
Mars
1.85°
Jupiter
1.31°
Saturn
2.49°
Uranus
0.77°
Neptune
1.77°
Pluto
17.15°
Zodiac Constellations
• As earth
revolves,
sky appearance
changes.
• Constellations
around ecliptic
called Zodiac
Galactic System
• Study Milky Way and
beyond
• Plane of Galaxy
• Inclined about 63 deg
to Celestial Equator
Galactic System
• Fundamental plane =
plane of Milky Way
• Galactic Equator
• North Galactic Pole
• South Galactic Pole
• Center of Galaxy
Galactic Coordinates
•
•
•
•
•
•
•
Galactic Latitude
NGP = 90 deg
SGP = -90 deg
Galactic Longitude
Counterclockwise
0 to 360 deg
0 = center of our
galaxy
Coordinate Curriculum K-13
•
•
•
•
•
Elementary Activities
Middle School – Junior High Activities
Senior High Activities
Aligned to National Standards
Involve science, geography, math,
language arts, art, problem-solving
• Introductory, skill-development, and
assessment activities
Chandra
Related to
1. Chandra Classroom-ready activities as
Stellar Evolution, Variable Stars,
Electromagnetic Spectrum, Imaging for
Junior and Senior High
2. ds9 and Visual Observatory
3. Chandra Sky Map
Science Olympiad
Related to
1.Elementary Science Olympiad events in
Starry, Starry Night and Map Reading
2.Reach for the Stars and Road Scholar for
Division B
3.Astronomy and Remote Sensing for
Division C
4.Trial events as Global Positioning
Systems
Tools of Astronomy
• 3-d models, globes, grids, star maps, charts,
graphs, quadrant, astrolabe, cross-staff, pinhole
protractor, parallax, hand angles
• binoculars, telescope, star lab, planetarium
• Computer technology as Chandra Sky Map, ds9,
Remote Sensing, GPS, Sky Map programs
• Coordinates, measurements, angles, relative
positions, times, navigation
Sample Activity
• Chandra’s Stellar Evolution poster recently
in the Science Teacher magazine
• Map projections
• Coordinate grids
• Problem-solving
Chandra’s Stellar Evolution Poster
Map Projections
• Attempts to represent
sphere on flat map
• Always some
distortion
• Types to emphasize
specific regions of
sphere
Sky Maps
Whole Sky (Aitoff) Projection
• Whole sky projection is popular with astronomers
• Projections for Equatorial, Ecliptic, or Galactic Systems
Different Reference Planes
Mercator - Equatorial Region
• Shows the regions
near the equator
• Less distortion when
put on a flat surface
• Regions north and
south of equator
SC001 Equatorial Region
• Using Equatorial (RA-dec) System
SCOO1 - Declination
• Declination (latitude-like) from +60 deg above to -60 deg below
celestial equator.
• Degrees, minutes, and seconds of arc
SC001 – Right Ascension
• Right Ascension (longitude-like) from 0-24 hrs.
• Hours, minutes, seconds
• Hour circles “meridians” of Right Ascension
Polar Region
• Circumpolar region
• North version
• South version
SC002 - Declination
• North Version
• 30 – 90 deg
declination
• Parallels of
declination
• Equatorial region not
visible
SC002 – Right Ascension
• North polar version
• RA = 0 to 24 hours
• Hour circles or
“meridians”
• Note the chart
symbols for objects
and magnitude
Coordinates
Polaris
Equatorial
Equatorial
J2000
B1950
Galactic
Ecliptic
RA
Dec
RA
Dec
L
B
Lon
Lat
02h31’ 49.08 “
89o15 ’50.8 “
01h 48 ’56.79 “
89o 01’43.4 “
123o16’ 50.0 “
26o27 ’41.0 “
88o34’03.3 “
66o06’05.3 “
37.954516o
89.264109o
27.236644o
89.028733o
123.280542o
26.461395o
88.567594o
66.101463o
• Longitude-like coordinate listed first
• Latitude-like coordinate listed second
• Equatorial coordinates will reflect epoch –
B1950 or J2000