How We Measure the Universe, Animated. Donating = loving Brain Pickings remains ad-free and takes hundreds of hours a month to research and write, and thousands of dollars to sustain. If you find any joy and value in it, please consider becoming a Member and supporting with a recurring monthly donation of your choosing, between a cup of tea and a good dinner: (If you don't have a PayPal account, no need to sign up for one – you can just use any credit or debit card.)
You can also become a one-time patron with a single donation in any amount: labors of love. Cosmology. Chapter index in this window — — Chapter index in separate window This material (including images) is copyrighted!. See my copyright notice for fair use practices. At first you might think that in order to understand the structure of something as large as the universe, which by definition contains everything there is, you would need some very powerful telescope to see to the farthest reaches of space and a complex theoretical model.
Actually, there are some powerful conclusions you can draw from observations with the naked eye. You will explore that first and then move on to conclusions you can draw from extending your eyesight. You will explore the basic questions that human beings have been asking themselves ever since we have walked the Earth: where did we come from and where are we going? Universe Contains Mass---Why has the Universe Not Collapsed? The universe is not empty. Olbers' Paradox and the Dark Night Sky Another simple observation is that the visible night sky is dark. Field Guide to X-ray Sources :: Supernovas & Supernova Remnants. Supernovas & Supernova Remnants Every 50 years or so, a massive star in our galaxy blows itself apart in a supernova explosion.
Supernovas are one of the most violent events in the universe, and the force of the explosion generates a blinding flash of radiation, as well as shock waves analogous to sonic booms. Supernovas were originally classified on the basis of their optical properties. Type II supernovas show conspicuous evidence for hydrogen in the expanding debris ejected in the explosion; Type Ia explosions do not. Recent research has led to a refinement of these types, and a classification in terms of the types of stars that give rise to supernovas.
A Type II, as well as Type Ib and Type Ic explosion, is produced by the catastrophic collapse of the core of a massive star. A Type Ia supernova is produced by a sudden thermonuclear explosion that disintegrates a white dwarf star. Some Type I supernovas show many of the characteristics of Type II supernovas. Core-collapse Supernovas. YouTube. YouTube. YouTube. Teach Astronomy - Cosmological Principle. Parsec Definition. Astronomical distance units -parsecs, light years and AU.