Expansion of the universe The universe we live in is not flat and unchanging, but constantly expanding. Progress is made by cycling through the scientific process of hypothesis, prediction, measurement, theory, hypothesis, Links: Orion Nebula Learn about some Hubble Space Telescope images that were taken in this region and about proplyds, objects which might be young solar systems that we are catching during formation. Silicate minerals, organic compounds, H2O, CO2, and CO ices, and a variety of molecular and ionic species have been found on comets, which contain more abundant volatile phases than asteroids see reviews by Spinrad, ; A'Hearn, Chapman, M.
Why are terrestrial planets denser than jovian planets? The law of conservation of angular momentum According to our present theory of solar system formation, what best explains why the solar nebula ended up with a disk shape as it collapsed? Age may only be a number, but when it comes to the age of the universe, it's a pretty important one.