1. Can you define the Astronomical Unit? A Light-Year?
Astronomical unit- The mean distance between the Earth and the sun, about 98 million miles or 150 million kilometers. It is often abbreviated as AU.
Light-year-A unit of astronomical distance equivalent to the distance that light travels in one year, which is 9.4607 × 1012 km (nearly 6 trillion miles).
2. What is a planet, a solar system, the Milky Way, a galaxy, the universe?
The largest scale is the universe itself, which is the sum total of all matter and energy. The largestknown organized structures are superclusters of galaxies, then clusters and groups of galaxies, and then the roughly 100 billion individual galaxies, most of which are many thousands of lightyears across. Each galaxy contains billions of stars, and many or most stars may be orbited by planets.
3. What is our place in the universe?
Our cosmic address
4. How did we come to be?
Big Bang 14 billion years ago
Chapter 2 – Discovering the Universe
5. How do the various celestial objects appear to move across the sky as the Earth rotates?
6. How does this apparent movement change as we view it from different latitudes on the
7. What is the celestial sphere? Can you define the following? an imaginary sphere of which the observer is the center and on which all celestial objects are considered to lie. Celestial equator and poles Vernal and autumnal equinoxes
Celestial equator- the projection into space of the earth's equator; an imaginary circle equidistant from the celestial poles.
Vernal and Autumnal- the time when the sun crosses the plane of the earth's equator, making night and day of approximately equal length all over the earth and occurring about March 21 (vernal equinox or spring equinox) and September 22 (autumnal equinox) Zenith Summer and winter solstices
Zenith- the highest point reached by a celestial or other object, directly above observer.
Summer solstice- longest day, Winter solstice- shortest day Horizon Declination-As seen from locations in the Earth's Northern Hemisphere, celestial objects with declinations greater than 90° − φ (where φ = observer's latitude) appear to circle daily around the celestial pole without dipping below the horizon, and are therefore called circumpolar stars. a boundary that divides what we can see from what we cannot see Celestial meridian- - a half circle extending from your horizon with an altitude at zero degrees, due south, through your zenith, to your horizon due north
Right ascension- The angular distance of a celestial body or point on the celestial sphere, measured eastward from the vernal equinox along the celestial equator to the hour circle of the body or point and expressed in degrees or hours. Ecliptic Altitude The angular distance north, counted positive, or south, counted negative, measured from the ecliptic along a great circle drawn through the pole of the ecliptic plane and a celestial body.-
8. How does the length of time a star spends above the horizon depend on its declination and on the observer’s latitude?
9. How much of the sky can you see from a given latitude?
Depends on location
10. Can you find your latitude from the altitude of the celestial pole? yes 11. How do the rising and setting times of the stars change from day to day and from month to month? How do the Moon’s rising and setting times change on a daily basis? Why do these changes occur?
12. What is the explanation for the Moon’s phases?
13. Can you tell the approximate rising and setting times of the Moon for each phase? Where should you look for the Moon at a given phase and time of day or night?
14. What is the Moon’s rotation period? What is its period of revolution?
15. What are the different types of eclipses? What causes eclipses? Why don’t eclipses occur every month? 16. Why do we have seasons? Why are there more hours of daylight in summer than in winter? How does the length of daylight depend on our latitude? Why