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Mercury before sunrise: start watching now
Look for Mercury before sunrise! Greatest elongation happens October 25. This is the Northern Hemisphere's best Mercury apparition of 2021.
October 21, 2021
Orionid meteor shower: All you need to know
In 2021, the Orionid meteor shower is expected to peak on the morning of October 21. But the just-past-full Hunter's Moon will interfere.
October 20, 2021
The full Hunter’s Moon is October 20
Find the date and time of the Northern Hemisphere's full Hunter's Moon for October 2021, and learn why this moon brightens the evening for a string of days.
October 20, 2021
International Observe the Moon Night is tonight
International Observe the Moon Night is October 16, 2021. It's a global event for celebrating the moon. Here's how you can participate online or in person.
October 16, 2021
How big are asteroids? See comparative 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.
October 14, 2021
What are star trails, and how can I capture them?
What are star trails? Photographers point cameras skyward and take long-exposure photos. You see streaks caused by Earth's rotation.
October 13, 2021
Proxima Centauri, closest star to our sun
Proxima Centauri is the nearest star to our sun at 4.22 light-years away. It's home to at least 2 planets and massive solar flares.
October 10, 2021
Mars in conjunction with sun October 7-8
Why is Mars sometimes bright? On October 7-8, 2021, Mars is in conjunction with the sun. What to expect from Mars in late 2021 and 2022.
October 5, 2021
Can you see the Big Dipper in autumn?
The Big Dipper is easy to recognize at most times of year. But the Big Dipper in autumn rides low in the northern sky in the evening hours.
October 4, 2021
Taurid meteors fly, now through December
The South Taurid meteors rarely produce more than 5 meteors per hour, but has been known to produce fireballs. When to watch in 2021.
October 2, 2021
