Enjoying EarthSky? Subscribe.

145,452 subscribers and counting ...


Does dark matter cause mass extinctions?

This painting by Donald E. Davis depicts an asteroid slamming into tropical, shallow seas of the sulfur-rich Yucatan Peninsula in what is today southeast Mexico. The aftermath of this immense asteroid collision, which occurred approximately 65 million years ago, is believed to have caused the extinction of the dinosaurs and many other species on Earth.

Does dark matter play a role in space impacts, such as the one that may have killed the dinosaurs approximately 66 million years ago? This painting is by space artist Don Davis via Wikimedia Commons.

Earth detectors haven’t yet detected dark matter. We know it’s there only because dark matter interacts, gravitationally, with visible matter and radiation. Modern theories suggests that dark matter makes up a substantial portion of the mass of our universe, and the inner part of our galaxy, where our solar system resides, is thought to contain dark matter. This month – in a paper published February 18, 2015 in the Monthly Notices of the Royal Astronomical Society - a New York University (NYU) professor cites dark matter as the cause for earthly catastrophes, specifically mass extinctions and geologic upheavals. The idea seems far-fetched, but has an easy-to-visualize logic behind it.

When is the next leap year?

2012 was a leap year.  2015 is not.  Image via free-printable-calendar.net

2012 was a leap year. 2015 is not. Image via free-printable-calendar.net

No leap year in 2015. The next leap day will be February 29, 2016. The reason for leap years explained here.

High risk for future U.S. megadroughts

Image Credit: NASA.

Image Credit: NASA.

The U.S. Southwest and Central Plains are at high risk for a megadrought later this century if greenhouse gas concentrations continue to rise, says a new study.

Roaming star system a near miss!

Artist's depiction of Scholz's star, a low-mass red dwarf star and brown dwarf companion (foreground) during its flyby of our solar system. The sun (left, background) would have appeared as a brilliant star.  Image via Michael Osadciw/University of Rochester.

Artist’s depiction of Scholz’s star, a binary star, during its flyby of our solar system. At this location – in the outer Oort cloud cloud – the sun (left, background) would have appeared as a brilliant star. Image via Michael Osadciw/University of Rochester.

Astronomers announced this week that they’ve now identified the closest known flyby of a star, really two stars, to our solar system. The culprit is a binary system consisting of a low-mass red dwarf star (with a mass about 8% that of our sun) and a brown dwarf companion (with a mass about 6% that of the sun). This pair passed through our solar system’s outer Oort comet cloud some 70,000 years ago. No other star is known to have ever approached our solar system this close – five times closer than the current closest star, Proxima Centauri.

Filmmakers look to world’s loneliest whale

Filmmakers Josh Zeman and Adrian Grenier are trying to raise funds toward bringing a whale known as 52 – sometimes called the world’s loneliest whale – to a movie theater near you. They want to mount a small oceanographic expedition to the North Pacific to find, track, tag and follow 52, last heard in 2012 but still thought to be out there.

This date in science: John Glenn first American to orbit Earth

John Glenn and Friendship 7

John Glenn and Friendship 7

February 20, 1962: John Glenn became the first American to orbit the Earth. He made three turns around the planet before returning safely in his spacecraft, Friendship 7.

This date in science: Happy birthday, Nicolaus Copernicus

This Flammarion engraving, by an unknown artist, is called Empedocles Breaks through the Crystal Spheres. Its original caption read: “A missionary of the Middle Ages tells that he had found the point where the sky and the Earth touch…”

February 19, 1473. Nicolaus Copernicus was born on this date, 541 years ago. Copernicus was a Renaissance astronomer and mathematician. He lived at a time when people believed Earth lay enclosed within crystal spheres at the center of the universe. Can you picture the leap of imagination required for him to conceive of a sun-centered universe? The publication of Copernicus’ book – De revolutionibus orbium coelestium (On the Revolutions of the Celestial Spheres) – just before his death in 1543, set the stage for all of modern astronomy. Today, people speak of his work as the Copernican Revolution.

Happy Chinese New Year 2015!

A woman poses with a sheep display in Hong Kong, which like many cities has put up colorful lunar New Year's decorations.  Image via Agence France-Presse.

A woman poses with a sheep display in Hong Kong, which like many cities has put up colorful lunar New Year’s decorations. Image via Agence France-Presse.

Over a billion people in China and millions around the world are celebrating the first day of the Chinese New Year on February 18-19, 2015. It’ll be February 18 according to U.S. calendars, and February 19 in Asia. It’s the most important of Chinese holidays, kicking off a celebration that lasts for 15 days. Each year is associated with one of 12 animals in the Chinese zodiac. For 2015, it’s the Year of the Sheep (Goat, Ram).

When space expanded faster-than-light

Artist's illustation via scienceblogs.com

Artist’s illustration of cosmic inflation via scienceblogs.com

New maps from the Planck mission support the theory of cosmic inflation, the idea that, in the moments following the Big Bang, space expanded faster than the speed of light. George Efstathiou – a leader in the Planck mission – explains more to the Kavli Institute’s Kelen Tuttle.

Lifeform of the week: Armadillos

I’ve been living in Texas for over six years now and blogging about animals for four of those years. And yet not once have I written about armadillos, a shameful omission which I will remedy today in this latest installment of Lifeform of the Week. Join me, dear reader, as there is much to learn…