Answer:
The reason is that, despite the distance, most objects / stars in the night sky, are not really that small, but appear very large.
Explanation:
While magnification in telescope helps to enlarge the object of focus, it is however, not always a good thing when doing astronomical viewing, due to the following reasons:
1. With higher magnification, a bigger object may not fit into the view, as a result of the total field view becoming smaller. For example, it will be easier to see the whole Andromeda galaxy on a small or low power view than on higher magnification.
2. Since most objects or stars in the sky are not so bright, applying higher magnification will make them look dimmer than necessary, thus will be difficult to observe. For example, during observation of Orion Nebula, it will be difficult to observe the body, if the telescope is magnified than necessary.
3. The presence of atmosphere or atmospheric conditions on earth also affects the telescope or magnification, as a clear and steady atmosphere helps the imaging of telescope to be sharp, while the unclear and turbulent atmosphere makes the imaging to be less detailed.
