Download North Star

Astronomy Picture of the Day
The Constellation Orion
Labeling
Constellations
Bayer System
 Systematic
method to name all the stars
that we see.
 Names the brighter stars by assigning :
 1. constellation (using the Latin
possessive of the name)
 2. Greek letter (Alpha, Beta, Gamma,
Delta, Epsilon, . . .)
 Labeled in an approximate order of
decreasing brightness for stars in the
constellation.
Bayer System
 Example
Orion Constellation
Bayer System
 Example
Orion Constellation
 Betelgeuse is also called Alpha-Orionis
 Rigel is called Beta Orionis
Circumpolar Constellations
 Constellations
that appear year long
in the sky
 Big dipper
 Little dipper
 Draco
 Camelopardalis
 Cepheus
 Cassiopeia
The Zodiac
The
constellations
that fall on the
ecliptic.
Star Charts
and Coordinate Systems
Astronomy Picture of the Day
A Star Cluster in the Rosette Nebula
Astronomy Picture of
the Day
This striking pair of
galaxies is far, far
away ...
about 350 million
light-years from
Earth.
Astronomy Picture of the Day
The Constellation Orion
The changing stars
 The
stars we see change with time of
night and season of year - why?
 The sky is a sphere with Earth at the
center.
 Observer can see only sky above the
horizon
 horizon……..an imaginary plane
tangent to Earth at the observer
Earth and Sky Terms
 Latitude….LINES
PARALLEL TO
THE EQUATOR
 Longitude……LINES THAT RUN
FROM POLE TO POLE
 Prime Meridian…RUNS FROM
POLE TO POLE THROUGH…....
 ……….Greenwich England
Celestial sphere Terms
 North
Celestial Pole….same as
North pole
 South Celestial Pole….same as
South pole
 Celestial Equator……….Projection
of earth’s equator out to the sky

altitude - the angle of a star above the horizon

The North Star, Polaris, is not the brightest star in
the sky but remains in a fixed position in the sky.

The angle of Polaris above your horizon is the
same as your latitude in degrees.
Right Ascension
 Distance
R.A.
measured eastward
along the celestial equator from
zero point, called the vernal
equinox
 measured in hours and minutes
……. 15hr 10 min, 23 hr, 5 min
Declination
 Angular
(Dec)
distance above
or below the celestial
equator
 measured in degrees….
0o, 15o, 30o
SC002
 The
Star Chart
North Star
 The Big Dipper
 The Little Dipper
 Cassiopeia.
SC001
Star Chart
Little dipper
 Cepheus
 Draco
 Orion
 Gemini
 Find the coordinates of Betelgeuse.

Earth and Sky Terms
Right Ascension
 Declination
 Ecliptic
 Vernal Equinox
 Autumnal Equinox
 Summer Solstice
 Winter Solstice

Motions of the Sun
and Stars
 Daily
Motion
 Annual Motion.
Motions of the Sun and
Stars
Daily
Motion
The rising and setting of
the stars is caused by the
Earth’s rotation about its
axis.
Horizon Calendar
June
(Summer Solstice)
March & September
(Equinoxes)
December
(Winter Solstice)
Stonehenge
Astronomy Picture of the Day
Cosmic wreckage from the detonation of a massive
star is the subject of this official first image from
NASA's Chandra X-ray Observatory.
August 27, 1999
Motions of the Sun and
Stars
 Annual
Motion
 The Earth’s orbit around the
Sun causes different stars
and constellations to be
visible at different times
during the year.
The Ecliptic
 The
Sun’s apparent yearly path
among the stars.
 Tip the equatorial circle by 23.5°
around a line passing through
the Earth
Diurnal Motion
rotation of Earth from west to
east causes objects on
celestial sphere to appear to
rise in east and set in west
daily
Solar Day
The
time it take for the
earth to make one complete
rotation
Takes 24 hours
Sidereal Day
 One
rotation of the earth
measured by the position of the
stars
 It takes 23hours 56 minutes
Seasons 
 What
causes seasons on Earth?
 Answer: The tilt of the Earth's
rotational axis.
 Ecliptic: The path of our Sun
across the celestial sphere is
called the.
 It is inclined 23½° with respect
to the celestial equator.
Earth and Sky Terms
Right Ascension
 Declination
 Ecliptic
 Vernal Equinox
 Autumnal Equinox
 Summer Solstice
 Winter Solstice

Inclined Pole causes Seasons