Here's why:

* Exosphere: The exosphere is the outermost layer of the Earth's atmosphere, gradually fading into space. It's extremely thin and can't support a spacecraft like Hubble.

* Hubble's Orbit: Hubble orbits Earth at an altitude of approximately 547 kilometers (340 miles). This is well above the exosphere and even above the thermosphere, which is the second-to-last layer of the atmosphere.

The key reason Hubble is in space is to avoid the distorting effects of the Earth's atmosphere:

* Light Absorption: The atmosphere absorbs much of the light from distant objects, making it difficult to observe them from Earth's surface.

* Turbulence: The atmosphere is constantly moving, creating turbulence that blurs images taken from Earth.

By orbiting above the atmosphere, Hubble can capture incredibly clear images of distant stars, galaxies, and other celestial objects.