exam 1 Flashcards
The sky above
Earth is NOT at the center of the Universe, but there is a
powerful tool to localize celestial objects, as if the sky was
turning around us: the celestial sphere
Zenith
The top of the dome, just above
your head
apparent motion
due to
Earth’s day/night cycle, and stars are
not glued to the dome, but rather
very distant from our planet.
Horizon
The line where the dome meets
the Earth
Earth’s axis
Imagine a line going through Earth, connecting the North and
South Poles.
north celestial pole and the
south celestial pole.
If we extend this imaginary line outward
from Earth, the points where this line
intersects the celestial sphere
Vernal (Autumnal) Equinox
When sun crosses celestial equator. Day and night of equal duration.
Summer (Winter) Solstice
Most northern (southern) point of the sun on the celestial sphere.
Ecliptic Tilt
Due to the tilt of Earth’s rotational axis relative to the orbital plane around the sun.
What is the path that the Sun follows through the constellations?
the ecliptic
Tropical year < sidereal year, due to precession of Earth’s axis
front of card
Zodiac
- The 12 constellations the Sun
moves through during the year.
deduce which stars lie behind
and beyond the Sun
observing the
stars visible in the opposite direction at
night.
Constellation
bright stars that are
grouped together
The first fairly accurate determination of Earth’s diameter was made in
200 BCE by Eratosthenes