Consider the following statements regarding light pollution:

1. Skyglow is the brightening of the night sky over inhabited areas due to artificial lights such as streetlights and security floodlights.

2. Glare refers to excessive brightness that causes visual discomfort.

3. Light trespass occurs when light falls where it is not intended or needed.

4. Clutter describes bright, confusing, and excessive groupings of light sources.

How many of the above statements are correct?