Our Place in Space

____________________- the distance between the Earth and the Sun - this is handy for comparing distances to planets within our solar system.

• Astronomical Unit

• Light Year

• Parsecs

____________________- the distance that light travels in one year (note that this is not a measure of time, it is a measure of distance).

• Astronomical Unit

• Light Year

• Parsecs

____________________- this is the distance at which the orbital radius of the Earth subtends one arcsecond (or 1/3600 of a degree)

• Astronomical Unit

• Light Year

• Parsecs

Useful for measuring distance within the Solar System.

• Astronomical Unit

• Light Year

• Parsecs

This unit is handy for describing distances to stars within our galaxy.

• Astronomical Unit

• Light Year

• Parsecs

Simplifies our calculations for distances to stars that are measured with trigonometric parallaxes. Equals 3.26 ly

• Astronomical Unit

• Light Year

• Parsecs

Astronomers use an _______________-centric coordinate system for viewing other stars. This coordinate system was inherited from the ancient (and incorrect) belief that the ____________ was motionless and that everything else - the planets, stars and the Sun - revolved around the _______________.

• Sun

• Earth

• Moon

• Self

The ______________ is the great circle where the sky "touches" the Earth, and this will also be observer-centric.

• horizon

• meridian

• celestial

• ecliptic

The __________________ is an arc that runs between the celestial poles (the projection of the Earth's north and south poles) and the zenith.

• horizon

• meridian

• celestial

• ecliptic

There are absolute positions that do not depend on the location of the observer. The equator of the Earth is projected into space as the "______________" equator.

• horizon

• meridian

• celestial

• ecliptic