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On the day of an equinox, the center of the sun would set about 12 hours after rising – given a level horizon, as at sea, and no atmospheric refraction.
Milestones for Cassini’s final week at Saturn. Today’s distant flyby of the large moon Titan will slow down the spacecraft enough so that – on Friday – Cassini will make its final plunge into Saturn’s atmosphere.
No matter where you live worldwide, Capricornus the Sea-goat climbs highest in the sky in early September. How to see it, and how a sea-goat came to reside among the stars.
“Ice, by itself, is only capable of flowing at velocities of no more than tens of meters per year. That means the ice is being helped along. It’s sliding on water or mud or both.”
For 32 years, scientists have tracked the oxygen-depleted waters that appear each summer in the Gulf of Mexico. This year’s dead zone is the biggest yet.
NASA’s Balloon Program is preparing new missions, including one designed to investigate the birth of our universe.
Another erroneous and misleading meme is going around about an August 12, 2017 meteor shower. Will it light up the whole sky? Be the best in 96 years? Sorry. No.
How to find Sagittarius on August evenings, plus the lore and science of this constellation.
These two famous stars shine down from the northern sky. Eltanin and Rastaban represent the fiery Eyes of the constellation Draco the Dragon.
Whether you’re a beginning stargazer or a veteran of thousands of starry nights, binoculars can be your best friend.
One side of the moon always faces Earth. Even so, over time, it’s possible to see as much as 59% of the moon’s surface, due to lunar libration.
EarthSky friends outdid themselves this weekend, taking photos of the full moon. Thanks to all who contributed!
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!
Venus will be 46 degrees west of the sun on Saturday morning, June 3, 2017. That’s about as far from the sun on our sky’s dome as it can be.
This very special young moon marks the start of the Muslim holy month of Ramadan. Very tough to spot on May 26 from locations east of the Atlantic, but the Americas had a better shot at it.
By at least 1 definition, the year 2017 has 4 supermoons. Three are new moons and not visible in our sky. The only full moon supermoon of 2017 will come in December.
This year’s list includes a spider and an ant with names drawn from popular books, a pink katydid and an omnivorous rat.
The constellation Virgo the Maiden fully returns to the early evening sky – with her feet planted on the eastern horizon – in early May.
With a final observation of remote galaxy cluster Abell 370, the Hubble Space Telescope’s mind-stretching Frontier Fields program came to an end.
Happy May Day! A few words about this annual celebration, which has its roots in astronomy.
It’s coming closer today than any asteroid this large since 2004. It came into view of small telescopes a few hours ago. Early radar observations indicate it’s bigger than we thought.
The scientists say their image, which combines images from more than 23,000 galaxy pairs, confirms dark matter’s existence. Will other astronomers agree?
The Big Dipper is easy. And, once you find it, you can find the Little Dipper, too. Plus … learn how the stars of the Big Dipper are moving in space.
Glorious photos of rare lenticular clouds, sometimes called UFO clouds, plus a word about how they form.
When a camera captures a star’s movement across the sky, it’s called a star trail. An astrophotographer explains how he does it.
Photos from the EarthSky community of the planet Venus – next planet inward from Earth in orbit around the sun – in early 2017, in a crescent phase.
Like all objects illuminated by sunlight, clouds cast a shadow.
March 2017 full moon is the 3rd of 3 full moons between the December solstice and March equinox. Harbinger of spring for Northern Hemisphere. Southern Hemisphere’s Harvest Moon.
People used to think that strong winds caused the rocks to move across Death Vally’s Racetrack Playa. Turns out, it’s not.
Here’s a beautiful image of a sliding (or sailing or slithering) stone at Death Valley’s famous Racetrack Playa. Cat Connor caught it on Christmas Day 2014.
An earthly lion guards the gates, while, in the sky, a celestial Lion – Leo – ascends. Astrophotographer Jeff Dai of China tells the story.
The giant panda’s distinct black-and-white markings have two functions: camouflage and communication, says a new study.
The occultation by the moon of Aldebaran – brightest star in Taurus the Bull – was visible from North America. Great set of photos here from the EarthSky community!
Here’s how to find the constellation Cancer in your sky. Plus Cancer’s place in sky history, lore and science.
An amazing several-state tribute – stretching across Tornado Alley – honoring Twister star Bill Paxton, who died Sunday due to complications from heart surgery.
At a very steady rate, unstable carbon-14 gradually decays to carbon-12. The ratio of these carbon isotopes reveals the ages of some of Earth’s oldest inhabitants.
The moon has returned to the evening sky. This week, it’s sweeping past brilliant Venus and fainter Mars. Photos from the EarthSky community, here.
The probability of another event like the 1859 Carrington event is – at any given time – low. But many believe it’s “almost inevitable” one will occur, eventually. A new study explores the risks.
Delay those New Year’s plans. World timekeepers will add a leap second just before midnight on December 31, 2016.
California has dry spells, but the state hasn’t had exceptional drought since at least 2000. Now, about 20 percent of California is in exceptional drought, and many trees have died.
Mount Hekla is Iceland’s 3rd most active volcano. A large eruption in 1104 earned it the moniker Gateway to Hell. Is Mount Hekla overdue for another eruption?
Many captured the full Hunter’s Moon last night. It was also the 1st of 3 supermoons in 2016. Thanks to all who contributed!
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.
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?
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.”
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.
People at high latitudes are seeing glowing clouds in a dark night sky. They’re called noctilucent or “night-shining” clouds.
Equinox moon and Jupiter next few days
Triple lightning hits the sea