Galaxies Besides computer simulations, what evidence do astronomers have to support the popular hypothesis that elliptical galaxies form from merging spirals?
Solar System I keep reading about Mars meteorites found on Earth. How do scientists know they came from Mars without samples of martian rocks to compare them?
Science If all photons have the same speed (the speed of light) and the same mass (zero), why does an individual gamma-ray photon have more energy than a radio-wave photon?
The Sun When the Sun produces a coronal mass ejection, is the blast of sufficient force to alter our star’s path through the cosmos? Do these eruptions significantly perturb our solar system?
