1. What is a constellation A group of stars is known as a constellation.

2. The Great Nebula (M42) in the constellation Orion, 1,600 light-years from the earth, consists of bright and dark masses of gas and dust where stars are in the process of being born. e. Ronald Royer/Science Source/Photo Researchers, Inc.[1] [1]"Orion Nebula," Microsoft® Encarta® Encyclopedia © Microsoft Corporation. All rights reserved.  

3. The various constellations with their shapes seen during the year

4. Hanging down from Orion's belt is his sword that is made up of three fainter stars. The central "star" of the sword is actually not a star at all, but the Great Orion Nebula, one of the regions most studied by astronomers in the whole sky. Nearby is the Horsehead Nebula (IC 434), which is a swirl of dark dust in front of a bright nebula.

5. What is the difference between a revolution and rotation

6. REVOLUTION =SEASONS The changing seasons are caused by the changing position of the Earth in relation to the sun.seasons keep changing because the tilt of the Earth's axis never changes while the Earth circles the sun. One way to understand this is to picture which way the tilt of the axis causes the North Pole to slant at different times of the year.  

8. A SEASON is one of the four periods of the year
A SEASON is one of the four periods of the year. Each season--spring, summer, autumn, and winter--lasts about three months and brings changes in temperature, weather, and the length of daylight.
During the spring, the days are warm in middle parts of the Northern Hemiphere, the northern half of the Earth. Summer follows with hot days and warm nights. In autumn, the days become cooler, leading to the cold of winter. The four periods are called climatic seasons when based on these temperature and weather changes.
In the Southern Hemisphere, the climatic seasons differ by about six months. This hemisphere has summer when the Northern Hemisphere has winter.  
WHAT IS A SEASON

9. DO SEASONS OCCUR EVERY WHERE?
Some regions do not have all four climatic seasons.
In parts of the tropics, for example, temperatures change little. But the amount of rainfall varies greatly, so that these regions have a wet season and a dry season.
The polar regions, on the other hand, have a light season and a dark season. In these parts of the world, the sun shines almost all the time in summer and almost never during the winter.  

10. What is rotation when an object. moves on its. own axis it is
What is rotation when an object moves on its own axis it is called rotation .

11. This phenomenon causes day and night