Earth may seem uninhabited to alien astronomers.

To determine the conditions on exoplanets, terrestrial astronomers analyze the properties of their surface and atmosphere using infrared and ultraviolet radiation. The spectra of the Earth, its thermal radiation, can correspond to both favorable characteristics for life and unfavorable ones. At the same time, it seriously differs in different parts of the planet and in different seasons. That is, it is impossible to obtain a single representative sample of the Earth's thermal radiation spectrum. This was shown by analysis of data from an infrared probe aboard NASA's Aqua satellite. This means that alien astronomers from a distant galaxy may not understand that there is life in the solar system. It will be very difficult to observe the dynamic Earth, analyze and interpret the data obtained.