Skywatching tips from NASA
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How do we study the stars?
Our best technology can send men to the Moon and probes to the edge of our solar system, but these distances are vanishingly small compared to the size of the universe. How then can we learn about the galaxies beyond our own? Yuan-Sen Ting takes us into deep space to show how astronomers study the stars beyond our reach.
The moon illusion
Have you noticed how the full moon looks bigger on the horizon than high overhead? Actually, the two images are exactly the same size -- so why do we perceive them differently? Scientists aren't sure, but there are plenty of intriguing theories. Andrew Vanden Heuvel unravels the details of focus, distance and proportion that contribute to this mystifying optical illusion.
A rare, spectacular total eclipse of the sun
How can the tiny moon eclipse the sight of the gargantuan sun? By sheer coincidence, the disc of the sun is 400x larger than the disc of the moon, but the sun is 390x farther from Earth -- which means that when they align just right, the moon blocks all but the sun's glowing corona. Andy Cohen details this extraordinary celestial phenomenon (and when it will next occur).
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