420 likes | 852 Views
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 ….
E N D
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 …
Big Dipper: Points to Polaris • http://www.astropix.com/HTML/C_SPRING/URSAS.HTM
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
Why care about finding Polaris? • The direction of Polaris is due North • The angle between Polaris and the horizon is YOUR LATITUDE • How can I measure angles?
Astronomy Picture of the Day (APOD) http://antwrp.gsfc.nasa.gov/apod/ap090627.html • Summer Triangle • http://antwrp.gsfc.nasa.gov/apod/ap090912.html • Winter Hexagon • http://antwrp.gsfc.nasa.gov/apod/ap021106.html
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
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.
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)