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On the day of the equinox, the center of the sun would set about 12 hours after rising – given a level horizon, as at sea, and no atmospheric refraction.
Here’s one you might not know … the intriguing relationship between supermoons and the famous 18-year Saros cycle of eclipses.
The Dawn spacecraft is still orbiting Ceres. It went into an extended mission mode on July 1. Some mission highlights and current thinking, here.
The constellation Capricornus the Sea-goat. How to see it, and how a sea-goat came to reside among the stars.
American astronomer Asaph Hall discovered Phobos, one of the two Martian moons, on this date in 1877. Did he imagine how well we’d see Mars’ moons today?
Perseid meteor shower peak was predicted for the morning of August 12. If you missed it, watch for meteors in a country sky between midnight and dawn Saturday morning.
You can see the constellation Sagittarius on August evenings. Look here for the lore and science of this constellation.
Humpback whales appear to rescue not just their own species, but also other whale species, seals and sea lions from attacks by killer whales.
“Parakeets are Britain’s fastest growing bird population and are on a trajectory to global domination.”
These two famous stars shine down from the northern sky. Eltanin and Rastaban represent the fiery Eyes of the constellation Draco the Dragon.
Delay those New Year’s plans. World timekeepers have announced they’ll add a leap second just before midnight on December 31, 2016.
NASA released this image as the Juno spacecraft arrived at Jupiter.
Planet K2-33b resides in a solar system in the process of being born. In human terms, if Earth were 45 years old, this planet would be just a few weeks old.
We’ve all seen virga, but maybe not known what it’s called. Virga is rain that evaporates before it hits the ground. Enjoy these photos!
People at high latitudes are seeing glowing clouds in a dark night sky. They’re called noctilucent or “night-shining” clouds.
While the massive and sudden colony collapses that occurred a decade ago have abated, honey bees are still dying at troubling rates.
The constellation Virgo the Maiden fully returns to the early evening sky – with her feet planted on the eastern horizon – by early May.
While preparing on Sunday to watch today’s transit – an event Mercury crosses the face of our sun – Helio C. Vital caught an airplane doing the same.
“Since three years ago, we have planned to shoot this photo. We went to the zone repeatedly but every time we got nothing … until now.” – Sergio Vindas
The meltdown at the Chernobyl Nuclear Power Plant on April 26, 1986 exposed 572 million people to radiation. It was far worse than the 2011 Fukushima accident.
As Earth spins under the sky, the stars appear to move. When a camera captures that movement, that’s called a star trail. Plus … an astrophotographer explains how he does it.
Many hoped Comet 252P/LINEAR would become visible to the eye. It has, but only barely. Enjoy photos from the few, the proud, who’ve captured this comet on film!
April 7 moon turns new six hours before perigee – closest point to Earth. We won’t see it, but it counts as a supermoon and will affect ocean tides.
Scientists have discovered a tiny 430-million-year-old sea creature – dubbed Kite Runner – that apparently dragged its offspring around on strings like kites.
Record-breakingly close flybys of two comets earlier this week. Radar images of one, the closest comet in 246 years. Will the other be visible to the eye?
We’ll have six supermoons in 2016. The first one is a new moon supermoon, not visible in our sky.
These lens-shaped clouds are often mistaken for UFOs. Here’s how they form, plus gorgeous photos.
As the list of known planets beyond our solar system grows, the search for their moons is intensifying. Why exomoons might be key to E.T. life.
First time we can see 5 planets at once since 2005. All 5 are up before dawn, still, and all 5 will remain visible until Mercury disappears in the dawn just after mid-February.
Best photos from the EarthSky community of the 5 bright planets now visible at once in the sky before dawn. Thanks to all who posted!
Claims about new planets that turned out to be wrong – and why ‘Planet Nine’ may be different.
“What we have seen this past year will likely be routine in about 15 years, although regionally the details will vary considerably,” says climate expert Kevin Trenberth.
Comet C/2013 US10 (Catalina) has been a wonderful target for photographers. See photos of this icy visitor from the depths of space, here. Thanks to all who submitted!
Moon passes in front of, or occults, bright star Aldebaran tonight as seen from N. America, and parts of Europe and Africa. Plus … Aldebaran as part of a double pole star.
A million thanks to you who posted photos on EarthSky pages of Venus and Saturn Saturday morning! Closer than any two planets since 2013 …
Are supermoons hype? In our opinion … no, just modern folklore. And they cause real physical effects, such as larger-than-usual tides.
Click here for a video visualization of events leading to one of the iconic photographs of the 20th century – Earth rising over the moon – as seen by Apollo 8 astronauts.
Most work on time travel has focused on its theoretical aspects, but there are also attempts to simulate the effects of time travel experimentally.
Over the past 14,000 years, penguin numbers in East Antarctica increased 135-fold because of disappearing glaciers and sea ice. How long can populations keep growing?
With COP21 poised to begin in Paris, a new UN report suggests that weather-related disasters were nearly twice as frequent over the past decade as two decades ago.
Hole-punch clouds are sometimes called fallstreak holes. They are often-circular patches of clear sky, surrounded by clouds. Airplanes create them.
The mysterious grooves on Phobos are likely early signs of structural failure. Scientists expect the moon to be pulled apart in 30 to 50 million years.
It might look like a UFO – but it’s really a hole-punch cloud. A word about the classic connection between hole-punch clouds, jets and snowfall.
People in Los Angeles and various states in the U.S. West saw the mysterious light. It was confirmed as a Naval missile test off the California coast.
Last week heralded as largest known asteroid to pass Earth until 2027. Swept within 1.3 times the moon’s distance on October 31. Now thought to be a comet!
If you’re a beginning stargazer or a veteran of thousands of starlit nights, binoculars can be your best friend. Here’s how to get started.
It’s the largest astronomical image of all time, used by astronomers in the search for distant exoplanets and multiple star systems.
If you could see the shock wave from a jet moving faster than sound, this is what it would look like.
October has two birthstones – opal and tourmaline.
Many features on Charon informally named from science fiction, particularly Star Trek and Star Wars. Lord of the Rings, Stanley Kubrick also honored.
Can you find the Big Dipper?