Look again at the loop of hot gas in this X-ray image. Suppo… Look again at the loop of hot gas in this X-ray image. Suppose we took another photo looking at the same place 1 hour later. What would we se Read Details
In the formula E = mc 2, what does E represent? In the formula E = mc 2, what does E represent? Read Details
Professional astronomical telescopes generally have a much g… Professional astronomical telescopes generally have a much greater magnification than the telescopes you can buy in stores. Read Details
Which is the strongest of the fundamental forces in the univ… Which is the strongest of the fundamental forces in the universe? Read Details
One light-hour is the distance that light travels in an hour… One light-hour is the distance that light travels in an hour. How far is this, in kilometers? (Recall that the speed of light is 300,000 km/s.) Read Details
How would the apparent brightness of Alpha Centauri change i… How would the apparent brightness of Alpha Centauri change if it were three times farther away? Read Details
Consider an atom of gold in which the nucleus contains 79 pr… Consider an atom of gold in which the nucleus contains 79 protons and 118 neutrons. What is its atomic number and atomic weight? Read Details
What are the dark blobs (indicated by the red arrows) in thi… What are the dark blobs (indicated by the red arrows) in this photograph from the Hubble Space Telescope? Read Details
