Cosmological Lookback Time Calculator
When you point your telescope to some distant galaxy, what you see isn’t what it is; it’s what it was. And that difference, between when … Read More
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Hubble Distance Calculator
Maybe you picture the universe like a stage with stars and planets sitting still while you travel about among them. Instead, idea of expansion revealed … Read More
Hubble Law Recession Velocity Calculator
The beauty of Hubble’s idea, which was surprisingly elegant, was this: The more distant a galaxy is, the further away it moves; and all those … Read More
Redshift Calculator
That’s where Redshift comes in. It is sort of like Doppler shift, except instead of moving closer or farther from an object, we’re stretching out … Read More
Stefan-Boltzmann Power Calculator
Heat rises they say, right? And heat radiates, too. Your hand resting on a desk give off energy, as does a light bulb’s glowing filament. … Read More
Blackbody Radiation Calculator
Heat is light. Light is energy in motion within space. Any object at any temperature higher than absolute zero will emit this energy. The formula … Read More
Wien Law Peak Wavelength Calculator
Thermal radiation lets you see temperature. As an object warms, its heating element go from a dull red, to bright orange, to white hot. Its … Read More
Star Temperature From Color Calculator
The night sky looks black, with one big blotch of red in it. And the red looks familiar. It’s like the red of a ripe … Read More
Main Sequence Lifetime Calculator
But stars are not candles. In fact, they’re exactly opposite. A candle is made from burning it’s own waxy substance. As it gives off light, … Read More
Stellar Mass From Luminosity Calculator
The first thing most people notice when they look at a star is its brightness. But we all know appearances can be deceiving. A massive … Read More