Asterisms are small
groups of stars
which make familiar
shapes. Found
within constellations.
Nebula - a gas
cloud in which
stars can be
formed.
Nebulae
are faint,
fuzzy
patches
of light.
Stars
can be
used as
pointers.
Greek letters are used to
indicate the brightness of
stars. Eg. Alpha = brightest,
beta = 2nd brightest,
gamma = 3rd brightest, etc.
All stars
along the
ecliptic are
seasonal.
Declination and
right ascension
used for
co-ordinates.
Celestial equator
has a declination
of 0 degrees.
North of the
equator is positive,
south is negative.
Right ascension is
measured from the
point on the celestial
equator where the
Sun passes from the
Southern to the
Northern Hemisphere.
Ecliptic - eastward path of the Sun
Zodiacal Band - 8
degrees either side
of the ecliptic.
Circumpolar star -a star that never
sets below the horizon from a
location. A star is circumpolar is
declination > 90 - latitude
Stars appear
to rise in the
East and set
in the West.
Stars are said to
culminate when
they cross the
meridian.
Culmination of a star is
the best time to observe
it because there is less
atmosphere between the
star and the observer, so
it appears brighter. This
is because there is less
atmosphere to absorb the
light.
Right Ascension < >
In history they
thought the Solar
System was
geocentric. It is
actually
heliocentric.
The Sun, Mercury, Venus,
Earth, Mars, Jupiter, Saturn,
Uranus, Neptune
In the Solar System there are 8 planets,
satellites, the Sun, dwarf planets, comets,
asteroids, Trans-Neptunian Objects, and
centaurs .
Centaur - half comet, half asteroid in
behaviour..
Pluto is now a dwarf
planet, because planets
must: be large enough to
be spherical, be in orbit
around the Sun, have
cleared its orbit of other
objects.
1 AU is distance between the Earth and Sun.
Longer man missions than to
the Moon have lots of
problems.