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Why time travel isn’t possible

Why does time flow inexorably toward the future? A Berkeley physicist proposes that time is expanding because space is expanding.

Last hurrah of sunlike star

New Hubble image shows the demise of a sunlike star. Our own sun will also burn out and shroud itself with stellar debris, but not for another 5 billion years.

Cassini begins epic final year at Saturn

The spacecraft will plunge repeatedly between Saturn and its rings, and finally execute a headlong plummet into the body of Saturn itself.

Melting sea ice leaves polar bears hungry

“Sea ice really is their platform for life. They are capable of existing on land for part of the year, but the sea ice is where they obtain their main prey.”

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Today in science: Discovery of Neptune

Neptune is the planet discovered with mathematics.

Last quarter moon is September 23

Fun time to see a last quarter moon: just after it rises, shortly after midnight. Then the lighted portion points downward, to the sun below your feet.

Late September-October planet guide

Use the moon to catch Mercury before dawn in late September, 2016. Then watch as Jupiter pairs with Mercury in the picturesque glow of dawn on October 11.

All you need to know: September equinox

2016’s September equinox arrives on the 22nd. Happy autumn (or spring)!

A Chinese perspective on autumn

Autumn is connected in Chinese thought with the direction west, considered to be the direction of dreams and visions.

Today in science: Michael Faraday

Meet Michael Faraday, the man behind the electric motor and theory of electromagnetism.

Astro festivals, star parties, workshops

Looking for something to do on the weekends? At star parties, amateur astronomers with telescopes will show you the night sky. Find one near you …

Dwarf galaxies and dark matter update

Standard cosmology calls for many more dwarf galaxies than we see. A new computer simulation suggests we might not need so many dwarf galaxies, after all.

Fomalhaut had first visible exoplanet

Fomalhaut is sometimes called the Loneliest Star. Its planet, Fomalhaut b, was the first planet beyond our solar system to be visible to the human eye.