Robotic Spaceflight Hubble is in space and the mirror is exposed, so how has the mirror stayed clean? Is it possible that space debris and micro particles could hit it?
Stars How can we tell if a star belongs to a star cluster or is in the space between the cluster and the observer?
Cosmology Why isn’t dark energy considered the “fifth force” in the way gravity, electromagnetism, weak nuclear, and strong nuclear are forces?
Exoplanets Ask Astro web extra: Has anyone pointed a telescope toward Alpha Centauri to see if there are planets only 4 light-years away?
