mapping the celestial sphere locating stars and deep space objects
DESCRIPTION
Terms Cont’d Celestial Poles: Points on the celestial sphere directly above the North and South Pole Celestial North Pole: Has the North Star, Polaris Celestial South Pole: Has no Southern StarTRANSCRIPT
Mapping the Celestial sphere
Locating stars and deep space objects
Important Terms Celestial: Anything
referring to the “heavens”, or space above us
Celestial Sphere: The night sky that looks like it is a painted dome above us
Terms Cont’d Celestial Poles: Points on
the celestial sphere directly above the North and South Pole
Celestial North Pole: Has the North Star, Polaris
Celestial South Pole: Has no Southern Star
Terms Cont’d
Celestial Equator: The line on the celestial sphere that is directly over the equator
Terms Cont’d Zenith: Imaginary
point on celestial sphere directly overhead (90°)
Nadir: Exact opposite of the Zenith You cannot
see it
Terms Cont’d Horizons: Place
where the earth and sky appear to meet Halfway between
zenith and nadir
2 terms we use to describe objects’ locations
1. Declination = Celestial Latitude Measured in Degrees
2. Right Ascension= Celestial Longitude Measured in time.
Location of a star Betelgeuse
RA: 5h 55m 10.2s east of vernal equinox
Dec: 7°24’26” north of celestial equator
HOW WE LOCATE STARS IN THE CELESTIAL SPHERE
3Ways: 1. Finding it relative to other markers (Celestial
equator/poles, zenith, horizon, etc…) 2. Finding it within a constellation (often in
terms of brightness) 3. Using Right Ascension and Declination
Constellations Constellations: A group of stars that appear to
form a pattern in the sky.
Starlight, Star Bright…. The 1st method of categorizing the brightness of stars: Magnitude
6 = barely seen with the unaided human eye. 5 = 2.5 times as bright as a 64 = 2.5 times as bright as a 53 = 2.5 times as bright as a 42 = 2.5 times as bright as a 31 = the brightest (then)
Apparent Magnitude Rating system has added numbers lower than 1 for VERY bright stars and numbers higher than 6 for objects only able to be seen by a telescope.
System of rating is dependent on how the star appears from Earth.
Bayer Designation System Naming stars within constellations
A Greek letter is given to each star in the constellation according to it brightness.
The brightest star is the “alpha star”, the next brightest is the “beta star”, and so forth.
Bayer Designation System & Apparent Magnitude
Star Bayer Designation Apparent Magnitude
Sirius Alpha Canis Majoris -1.46 Vega Alpha Lyrae 0.03 Rigel Beta Orionis 0.12 Betelgeuse Alpha Orionis 0.7 Antares Alpha Scorpii 0.96 Polaris Alpha Ursae Minoris 2.02
Constellation VisibilitySummer Winter
Earth Moves around the sun = different position
Constellations Changing Shape
Stars move at very fast speeds, from 3 to 122 km/s
Stars are so very far apart and so very far from us, they do not appear to change at all.
The constellations do change over very large time periods, however.