The reason we can't see stars all around us at night, despite Earth being a spherical object, is due to several factors:
Atmospheric Scattering: Earth's atmosphere scatters and absorbs light from distant stars, making it difficult to see them during the daytime. This scattering effect is caused by the interaction of light with particles and molecules in the atmosphere. At night, although the scattering is reduced, it still exists and can limit the visibility of stars, especially near the horizon where the path through the atmosphere is longer.
Light Pollution: Human-made light pollution from cities, towns, and other sources can significantly diminish our ability to see stars. The artificial light creates a bright background glow that obscures the fainter stars in the night sky. In heavily populated areas, light pollution can be particularly pronounced, making it challenging to observe stars even when away from the direct influence of atmospheric scattering.
Earth's Rotation: As Earth rotates on its axis, stars appear to move across the night sky. Due to the rotation, only a portion of the sky is visible to an observer at any given time. Stars that are below the horizon are not visible to us, and the specific stars we see change throughout the night as the Earth continues its rotation.
Stellar Brightness and Density: While the universe is vast and contains billions of stars, they are not distributed evenly. Some regions of the sky have more stars, while others have fewer. Additionally, the brightness of stars varies, with some being much fainter than others. These factors, combined with the limited field of view of the human eye, result in only a fraction of the stars being visible at any given time.
Overall, the combination of atmospheric scattering, light pollution, Earth's rotation, and the brightness and density of stars leads to the situation where we cannot see stars all around us at night, even though Earth is a spherical object. However, in dark and remote locations away from urban areas, with clear skies and minimal light pollution, one can witness a more extensive and awe-inspiring view of the starry night sky.