Transcript Stars, Constellations, and Quasars

Stars, Constellations,
and Quasars
Everything you ever wanted
to know (and maybe more)
Created for the sixth grade students of
American Preparatory Academy (2007)
Movement of Stars
Earth orbits the Sun in about 365¼
days. During this orbit Earth rotates
like a spinning top with its axis always
pointing in the same direction. On or
around June 21 the north pole is most
tilted toward the Sun. This point in
Earth’s orbit is the northern
hemisphere’s summer solstice. On
that day the Sun is directly above
the Tropic of Cancer (23½° north
latitude).
Movement of Stars
Six months later, around December
21, the north pole is tilted away
from the Sun to its greatest extent.
This is the northern hemisphere’s
winter solstice, and the Sun is
directly above the Tropic of
Capricorn (23½° south latitude)
Movement of Stars
Equinoxes occur midway between
the two solstices. The autumnal
equinox occurs around September 22,
and the vernal (Latin for “spring”)
equinox occurs around March 21. On
the equinoxes, there are 12 hours of
daylight and 12 hours of darkness
at every location on Earth. This is
because the Earth’s axis points
neither toward nor away from the
Sun. The Sun is directly overhead at
the equator during equinoxes.
Movement of Stars
Solstices and equinoxes mark the
beginnings of the seasons.
Because the northern hemisphere is
tilted away from the Sun when the
southern hemisphere is tilted toward it
(and vice versa), these hemispheres
have opposite seasons. It is winter in
the northern hemisphere when it is
summer in the southern hemisphere,
and it is spring in the northern
hemisphere when it is fall in the
southern hemisphere.
Movement of Stars
Sidereal time (star time) is
determined by the movement of
stars across the upper
meridian
Constellations
Constellations are visual groupings
of stars
Examples: Big Dipper, Orion, Little
Bear
Constellations
Virtually every ancient civilization
observed and studied the nighttime sky,
and archaeological evidence such as
Stonehenge points to these early
studies of astronomy. Ancient cultures
also developed elaborate mythologies
around stars and constellations and
gave them names, some of which are
still in use today.
Constellations
There are about 6,000 stars
visible to the unaided human eye.
Because we see only half the sky,
there are only about 3,000 stars
visible at any one time. To help
locate stars, astronomers use a
star map that divides the sky into
88 sectors named for a
constellation within each sector.
Constellations
Constellations
Some constellations and stars are very
familiar. These include Ursa Major (the
Great Bear), which includes the Big
Dipper, and Ursa Minor (the Little
Bear), which includes the Little
Dipper. Polaris, which is also known
as the North Star or the Pole Star, is
an important star in the handle of Ursa
Minor. Polaris takes its name from the
fact that Earth’s rotational axis
(north pole) points toward that
star.
Constellations
Ursa Major (the Great Bear)
including the Big Dipper
Constellations
Ursa Minor (the Little Bear)
including the Little Dipper and
Polaris (the North Star)
Constellations
Other constellations that are easy
to identify are Canis Major;
Canis Minor; Orion in the winter
and spring; and Cygnus, Lyra,
and Aquila in summer and fall.
These constellations include
the brightest stars in the sky.
Constellations
Canis Major
Constellations
Canis Minor
Constellations
Orion
Orion’s Belt
Constellations
Can you
find
Cygnus,
Lyra,
and
Aquila?
And my personal favorite -
Camelopardalis
Quasars
Artist's impression of quasar GB1508 with
Chandra x-ray image from NASA
Quasars
QUASi-stellAR radio source
extremely bright and distant
active galactic nucleus
compact halo of matter
surrounding the central
supermassive black hole of a
young galaxy
Quasar as photographed
by Hubble
Do you have any
questions?
Have a beautiful day!
Then, look at the stars
tonight!
Bibliography
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http://imagine.gsfc.nasa.gov/Images/news/gb1508_xray_illustration.jpg
Core Knowledge Sequence, p. 153, ISBN: 1-890517-20-8
https://www.cdis.missouri.edu/exec/data/courses2/6412/lesson01.htm
http://images.google.com/imgres?imgurl=http://csep10.phys.utk.edu/astr161/lect/time/star
maplarge.gif&imgrefurl=http://daintonben.stumbleupon.com/&h=900&w=991&sz=25&tbnid=Sm
QWD8oD_1ZoPM:&tbnh=135&tbnw=149&prev=/images%3Fq%3Dstar%2Bmap%26um%3D1
&start=1&sa=X&oi=images&ct=image&cd=1
www.lindahall.org/.../websize/maps/0020021w.jpg
http://www.lynchandthestars.com/images/starmap.jpg
Google Image Search: Ursa Major, Ursa Minor, Canis Major, Canis Minor, Orion, Cygnus, Lyra,
Aquila