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What are red giants? Our sun will become one!
What are red giants? Most main-sequence stars, like our sun, will become one. Red giants swell to such a large size they can swallow their inner planets.
November 9, 2023
How big are asteroids? Compare sizes in this video
How big are asteroids? This video shows the sizes of 22 asteroids - ranging from tiny to vast - in comparison to New York City.
November 3, 2023
Some will see a partial lunar eclipse tonight
A shallow partial lunar eclipse takes place on October 28, 2023, visible in Europe, Africa, most of Asia and western Australia. Jupiter is the bright object nearby. Maps and details here.
October 28, 2023
Olbers’ paradox asks ‘Why is the night sky dark?’
Olbers' paradox asks why is space dark if the universe is filled with stars. The answer has to do with traveling light and red-shifting colors.
October 19, 2023
Guy Ottewell’s Astronomical Calendar 2024 is here
The popular and information Astronomical Calendar for 2024 by Guy Ottewell is available. It comes in either electronic or printed form. Learn more here.
September 28, 2023
Observing meteors: Top 10 tips for the Perseids
The 2021 Perseid meteor shower is rising to its peak and many are observing meteors. Here are our best 10 tips for watching this shower, or any other!
August 1, 2023
How does Earth look from outer space?
How does Earth look from space? You could see it from Neptune, but it's brighter from closer locations. Spacecraft photos tell the tale.
July 14, 2023
What are gravitational waves? Ripples in spacetime
First postulated by Albert Einstein in 1916 but not observed directly until September 2015, gravitational waves are ripples in spacetime.
June 29, 2023
Geminid meteor mystery solved? It was a collision!
Data from the Parker Solar Probe helped scientists discover that the Geminid meteor shower is most likely the result of a violent event on asteroid Phaethon.
June 25, 2023
Comet C/2021 T4 Lemmon is sweeping through southern skies
Comet C/2021 T4 Lemmon was discovered at Mount Lemmon Observatory in 2021. It's currently in the southern skies and might become bright enough for binoculars.
June 4, 2023
