1. Identify the ecliptic plane, what objects are located in the ecliptic plane. Explain or diagram why these objects appear to move or not move, relative to the horizon, during the year.Ecliptic Plane is the surface in which the Earth orbits around the sun. In the ecliptic plane, there are:

Planets in the solar system Constellations in the Zodiac (Các chòm sao hoàng đạo)

They move relatively to the horizon during the year because: Other planets in the solar systems move around the sun in different orbits in different

speeds thus they move relatively to Earth. The Earth moves around the Sun thus during the year, at different positions of the Earth

in its orbit, we can observe different constellations.

2. Site Polaris or during daylight be able to point to roughly where it would be located. Would Polaris be located in the same place in the sky if we were at the equator? Explain why or why not.Polaris is 40o up from the Northern horizon if observed from Fort Collins. At the equator, the Polaris appears at the Northern horizon, because on the celestial sphere, Polaris is approximately directly above the Earth’s North Pole.

3. Explain or diagram how the telescope used in the lab on the roof gathers light.It gathers light by having a large, reflective lens at its bottom. The lens reflects light to a triangular piece of glass which then redirects light to eyepiece and finally to the observer’s eyes.

4. Explain or diagram why objects appear different in the telescope than with the naked eye. This should include how different eyepieces change the magnification or field of view.Object observed by telescope is different from by naked eyes in two ways: brighter and larger. The lens in telescope is much larger than human eyes thus it gathers more light and lighten the image. The lens-eyepiece system provides magnification and enlarge the image.The magnification capability is measured by

Magnification = Lens Focal Length / Eyepiece Focal LengthThus the smaller the focal length of eyepiece is, the more a telescope can magnify an object and the smaller the field of view it has.

5. Explain and diagram the current phase of the Moon. The explanation or diagram must include the Sun, Earth, and Moon.Nếu các bạn đi thi vào Thứ Ba tuần sau 29/04/2014 thì Trăng ở đúng New Moon Phase. Những ngày khác có thể tham khảo website: http://stardate.org/nightsky/moon

6. Be able to identify the closest star to Earth and diagram its motion in the sky.The closest star to Earth is the Sun. Observed from Fort Collins, the Sun moves in the ecliptic plane in the sky from East to West and draws a line across the sky that makes with the horizontal line an angle of 40o. Images below.