Sky Watching Talk
Download
Report
Transcript Sky Watching Talk
Night Sky Watching
(Basics)
Stars Pivot around a Point
The North Celestial Pole
(NCP)
Special
spot on the sky that the Earth’s
rotation axis points to
Why special?
During the night the stars
appear to rotate around
this spot
Also
special (and useful) in other ways …
Watching Stars from the North
Pole
Constellations are Big
Big Dipper: Points to Polaris
http://www.astropix.com/HTML/C_S
PRING/URSAS.HTM
Finding Polaris
Lucky Breaks!
The
star Polaris is amazing close to
NCP (now)
The “pointer stars” in the Big Dipper
line up directly with Polaris!!!!
Big Dipper is circumpolar
constellation
–See it all night and all year
Polaris also called Pole Star, North
Star
Big Dipper
Why care about finding Polaris?
The
direction of Polaris is due North
The angle between Polaris and the
horizon is
How
YOUR LATITUDE
can I measure angles?
Big Dipper as Star Guide
Constellations
Astronomy Picture of the Day (APOD)
http://antwrp.gsfc.nasa.gov/apod/ap090627.htm
l
Summer Triangle
http://antwrp.gsfc.nasa.gov/apod/ap090912.html
Winter Hexagon
http://antwrp.gsfc.nasa.gov/apod/ap021106.html
Summer Triangle
Winter
Hexagon
Constellation Facts
Group
of stars all in roughly the same
direction from Earth, BUT …. Each has
its own different distance from the
Earth
– Therefore, NOT grouped together is space
From
Greek astronomers have
inherited the names of the
constellations: mythological figures or
animals
Different cultures on Earth each have
different names for the constellations
Constellation
Stars at
Different
Distances
from Earth
Visible Constellations change over a
year
May
have heard …
– “Orion is a winter constellation”
– “You can see Cygnus most of the summer”
Above
comments arise because you
cannot see the Constellations near
where the Sun is in the sky
– Sun so bright it washes out rest of stars
Since
Sun moves along the Ecliptic
over a year the constellations “away”
from the Sun change over a year.
Constellations on
opposite side of
Sun (Opposition)
The Zodiac
Band
of constellations closest to the
Ecliptic (Sun’s yearly path across the
sky)
Correspond to Horoscope “Signs”
–Astrology used to make predictions (not
science!)
Useful
for backyard astronomy:
Planets and the Moon can always be
found in the Zodiac
Width of the Zodiac belt ~ 18°
Mars
Saturn
Mercury
Naming Stars
Brightest star in
constellation Taurus
Greek name: α Taurus
Arabic name:
Aldebaran
“Al Debarren”
“The Follower”
(of the Pleiades)