photo credit: Paal Bentdal

The History of the Light Bulb

Here's what happens when a light bulb comes on and the filament is in air. Don't try this experiment at home unless you work with an adult (and even then be very careful).

The glowing filament rapidly heated the air around it, so the heated air expanded and formed the rising smoke column. But the rising gas cooled and became more dense, so it eventually stopped rising. Then the air at the top moved out to the side, forming the swirls in the photograph. To see the direction of flow within the rising air column, check out this drawing.

For an award-winning video showing how to make smoke rings and mushroom clouds, click here.

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Cardboard Tube Syllabus

What happens when each eye gets a different message? Try the activities in the Exploratorium's Cardboard Tube Syllabus to find out. For a related illusion--and a remarkable one--see Cheshire Cat.

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image credit: NASA, ESA, R. Sankret and W. Blair; image source

400-Year-Old Supernova Mystery

This false-color composite image (hi-res version) shows the remnants of Supernova SN 1604 in visible light, infrared, and x-rays. The violence of a supernova explosion typically produces a neutron star. For a rare observation of a neutron star in x-rays, see this ESA image.

WMAP's Universe: The Life and Death of Stars

To learn about the life cycle of stars, visit WMAP's Universe: The Life and Death of Stars. For much more on how stars die, see the Australian Telescope Outreach and Education's Post-Main Sequence Stars.