StarDate Podcast

Few Americans have to hunt wild game to survive the long, cold winter these days. But that hasn’t always been the case. Native tribes and European settlers alike had to stock up as the weather grew cooler. And they relied on an autumn full Moon for help: the Hunter’s Moon. And that Moon is coming up tonight. It’s the full Moon after the Harvest Moon, which appeared in September. Like the Harvest Moon, the Hunter’s Moon helped people prepare for winter. Its light made it easier to see deer...

We’ve seen details on the surfaces of only a few stars other than the Sun. Stars are just so far away that most of them look like nothing more than pinpoints of light, even to the biggest telescopes. And most of the ones where we have seen details are either giants or supergiants. One exception is Altair, one of the members of the bright Summer Triangle. It’s high in the south as darkness falls, and drops down the western sky during the night. Altair is in the prime of life. It’s a couple...

Much of what makes science work is following up. After the discoveries are made, more research is needed to fill in the details. And the launch window for a spacecraft that’s all about the follow-up opens next week. CHEOPS is a European mission that will study exoplanets — planets that orbit stars other than the Sun. It won’t hunt for new planets. Instead, it’ll make detailed observations of star systems with known planets. CHEOPS will look for the planets to pass in front of their parent...

The Sun is a giant nuclear reactor. Every second, it “fuses” together about 650 million tons of hydrogen atoms to make helium. Some of the hydrogen is converted to energy — less than one percent. That’s enough to keep the Sun shining brightly. Scientists have been trying to replicate that process here on Earth since the 1950s. They use two forms of heavy hydrogen. One is common in seawater, while the other has to be manufactured. Success could provide abundant power with no climate effects...

A mine in California holds the residue of collisions between dead stars. So do even bigger mines in China. The stellar “ash” consists of a set of chemical elements that are used to forge key parts of modern technology — from cell phones to batteries for electric cars. They’re known as rare-earth elements. Some are born inside stars similar to the Sun that have reached the ends of their lives. A slow “drip” of neutrons builds up heavier elements, which are expelled into space when the stars...

It’s summertime! Not here on Earth, of course. Instead, summer arrives today in the northern hemisphere of Mars. It’s the Red Planet’s longest season. It lasts about 178 Mars days, which is 183 Earth days. The seasons on Mars have the same cause as those on Earth: the planet’s tilt on its axis. Right now, Mars’s north pole tilts toward the Sun. That brings the long days of summer north of the equator. South of the equator, though, it’s the start of winter. And it’s a frigid season. Not...

It’s not easy to take a picture of a planet orbiting another star. A planet is much smaller than a star, and it’s so faint that it’s drowned out by the star’s brilliant light. A decade ago, though, Hubble Space Telescope managed to snap the first picture of an exoplanet. It orbits Fomalhaut, the autumn star. Fomalhaut is about 25 light-years away. It’s twice as big and heavy as the Sun, and about 16 times brighter. And it’s only one-tenth of the Sun’s age — about 450 million years. It’s...

Two well-known star patterns highlight the northern sky tonight. The Big Dipper is low in the north-northwest at nightfall, and in the northeast at first light tomorrow. And W-shaped Cassiopeia is just the opposite — in the northeast at nightfall, and north-northwest at first light. As that sequence suggests, both patterns make a big circle around the sky during the night. They circle the North Star, Polaris — the hub of the northern sky. All the stars in the northern hemisphere appear to...

The Moon slides down the southwestern sky this evening. It’s accompanied by Saturn, the second-biggest planet in the solar system. Saturn looks like a bright star to the right of the Moon. Sunlight illuminates about half of the lunar hemisphere that faces our way. In other words, the Moon is at first quarter. It probably sounds odd that it’s both a half Moon and a quarter Moon. But the two fractions describe different things. At first quarter, the Moon is one-fourth of the way through its...

An astronomer could probably spend an entire career studying a busy star system in the constellation Lyra. It’s a dynamic system in which two stars are changing as we watch. Beta Lyrae is about a thousand light-years away. The system appears to consist of several stars. But the most interesting are two that are quite close together — they’re only a few million miles apart. The stars probably were born about 25 million years ago. A study last year said that one of them was born about 10...

The most impressive tides on Earth vary by about 50 feet from high tide to low tide. But that’s barely a jiggle compared to the tides on Io, one of the moons of Jupiter. Its tides vary by the height of a 30-story building. That’s especially impressive when you consider that the rising and falling is in Io’s crust. The tides have a serious impact on Io, which is about the same size as our own Moon. They create hundreds of volcanoes — more than on any other world in the solar system. And...

The Moon has a couple of impressive companions this evening. Brilliant Jupiter is to the upper left of the Moon as night falls, with Antares closer to the lower left. Jupiter is the largest planet in the solar system. But Antares is something even more impressive: a supergiant star. It’s hundreds of times the diameter of the Sun, and tens of thousands of times brighter. At least it looks that way. We can’t be sure it’s actually still there. A supergiant ends its life with a titanic...

To most of us, the titles of most research papers are dense and dull. But a paper published in July would draw just about anyone’s interest: Death by Dark Matter. In the paper, researchers looked to see if people were being killed by a possible form of dark matter. The conclusion: We’re safe. Dark matter is far more abundant than normal matter — the kind that makes up stars, planets, and people. We can’t see dark matter because it doesn’t interact with normal matter. But we know it’s there...

ET may be phoning home, but he’s not calling anyone else — not that we’ve heard, anyway. So far, the most extensive search for extraterrestrial intelligence to date has turned up empty. But the project isn’t giving up. In fact, it’s expanding the search by adding new telescopes. Breakthrough Listen has been operating for about four years. It uses giant radio telescopes in the U.S. and Australia. They monitor billions of frequencies for signals from other civilizations. The project has kept...

Summer ended less than a week ago, but you can already get a preview of the evening skies of winter in the hours before sunrise. Winter’s evening-sky highlights include the constellations Orion and Gemini, along with Sirius, the brightest star in the night sky. All of them are in view by about 4 a.m., and are high in the sky at first light. Orion is in the south and southeast as dawn breaks. It’s best identified by the hunter’s “belt” of three fairly bright stars. The brightest stars in...

Venus is trying to climb into view in the evening sky. The planet is very low in the west at sunset, and it sets well before twilight fades. It’s the brightest object in the sky other than the Sun and Moon, though, so it’s worth a try. Venus is the second-closest planet to the Sun, so it’s inside Earth’s orbit. As a result, it always stays fairly close to the Sun in our sky. At best, it’s visible for a while after sunset or before sunrise. Venus passed behind the Sun last month. Now, it’s...

The galaxy is full of binary star systems — two stars bound together by gravity. The list includes pairs of massive stars. And when those stars die, they can leave behind heavy but invisible corpses: black holes. Astronomers haven’t seen a single black-hole binary. That’s not surprising, since black holes produce no energy. We know such binaries exist, though, because astronomers can hear them. They’ve detected the mergers of binary black holes as they spiral together. A black-hole binary...

A monster black hole sits at the center of the Milky Way Galaxy. And it’s probably surrounded by many thousands of smaller black holes. But that’s just the beginning. There could be hundreds of millions of black holes spread throughout the galaxy. A black hole is so heavy and dense that nothing can escape its gravitational pull — not even light. That means we can’t see a black hole on its own. But there are lots of indirect ways to see them, including their effects on the stars and gas...

Most stars end their lives with a blaze of color — an expanding bubble of gas and dust known as a planetary nebula. A comet-hunting astronomer, Charles Messier, discovered the first planetary nebula more than 250 years ago. It’s known as M27 — the 27th entry in Messier’s catalog of comet-like objects. A planetary nebula forms when a star exhausts the nuclear fuel in its core. The core collapses and eventually forms a dense, hot ember called a white dwarf. Radiation from the sizzling-hot...

A hard-to-see fox trots high across the sky on autumn evenings: the constellation Vulpecula. It’s not very big, and its stars are all faint. But it was the site of one of the most famous discoveries in astronomy history — one that briefly looked like it might be a sign of alien life. The constellation was first drawn in the late 1600s. It filled a void between several prominent constellations. Originally, it was known as Vulpecula et Anser — the little fox and the goose. Later, the goose...