StarDate

The stars on the rim of the galaxy are going for a ride. They’re bobbing up and down like the horses on a merry-go-round. They’re also rippling outward, away from the center of the Milky Way. The Milky Way consists of a thin disk of stars and gas that spans a hundred thousand light-years or more. For decades, we’ve known that the rim of the disk is warped like the brim of a wide hat. It’s bent upward on one edge, and downward on the opposite edge. A recent study found that stars on those edges are moving along a big wave. Astronomers looked at the locations and motions of more than 20,000 bright young stars logged by the Gaia space telescope. The stars are as much as 45,000 light-years from the galactic center. Gaia found that the stars are bobbing up and down as much as a thousand light-years above or below the plane of the galaxy. And they appear to be sliding outward at thousands of miles per hour. The wave might have been created by a close approach of a smaller galaxy hundreds of millions of years ago. Its gravity disturbed the tranquility of the Milky Way’s outer precincts – sending the stars there for a ride. Under dark skies, the Milky Way is in good view tonight. In early evening, it extends along the body of Cygnus, the swan, in the west-northwest; through M-shaped Cassiopeia, higher in the sky; then down between Orion and the twins of Gemini, in the east-southeast. Script by Damond Benningfield

Almost 11 million years ago, a large asteroid slammed into Earth, somewhere around Australia. It could have gouged a crater more than 15 miles wide, and devastated life across tens of thousands of square miles. So far, though, the only traces of it are 14 tiny glass beads. Combined, they weigh just 53 grams – as much as a slice of bread. The beads are known as tektites. They formed from melted rock and sand that was blasted into the sky. Tiny blobs were shaped into balls by their passage through the air. Tektites are found all across the planet. Most of them are associated with a few major impacts. The region where a group of related tektites is found is called a strewn field. Five confirmed fields had been identified. One of them stretches across Australia and Asia. Decades ago, scientists identified eight tektites as members of that field, which was created by an impact about three-quarters of a million years ago. But a recent analysis found otherwise. Scientists conducted extensive studies of those beads, along with six others. They found that the beads were related to each other – but not to the known strewn field. Instead, they formed a new field, which stretches almost 600 miles across Australia. The beads are all the same age. So they formed in the same impact – 11 million years ago. But no one has yet found a crater – only a tiny handful of beads from a possible cosmic impact. Script by Damond Benningfield

Farmers in the American breadbasket are used to weather troubles: floods, droughts, hail, and more. But a storm in May of 2024 was something new. It caused machinery to go haywire during the peak of planting season. That caused an estimated 500 million dollars in losses. What was different about this storm was its source: the Sun. Massive outbursts of particles and energy bombarded Earth. That caused impressive displays of the northern lights. But it also messed with GPS satellites. From the central United States, GPS positions were off by more than 200 feet. That messed with farm equipment, disrupting the planting. A recent study said that such breaks could be more common in the decades ahead. The Sun goes through an 11-year cycle of storms. Big storms can cause all kinds of problems for modern technology. A couple of recent cycles were unusually quiet. And forecasts had called for the same from the current cycle, which peaked in 2024 and ’25. But those forecasts were wrong. The current cycle has been much more active than the previous ones, with many more sunspots than expected, and many more big outbursts. The recent study said that upcoming cycles could be even busier. The solar wind has been getting stronger since 2008 – an indication that the Sun is waking up from a “sleepy” period. So farmers – and the rest of us – could see more space weather problems in the decades ahead. Script by Damond Benningfield

Earth is getting fainter. For proof, just look at the Moon – something that scientists have been doing for decades. They’ve been looking at earthshine – sunlight reflected off of Earth. We see it lighting up the nighttime portion of the Moon – the part that’s not brightly lit by the Sun. It gives that part of the Moon a ghostly appearance. Right now, most of the lunar hemisphere that faces our way is in earthshine. The Moon is a thin crescent in the early morning sky. It’s getting thinner by the day as it wanes toward “new.” From the Moon, though, Earth is getting fatter. It’ll be “full” in just a couple of days. How bright Earth looks varies a good bit, depending on the exact distance, the amount of ice and cloud cover, and other factors. Clouds and ice are bright; land and oceans are dark. So as Earth turns on its axis, and different features rotate into view, earthshine goes up and down like a dining room light on a rheostat. Earthshine varies over longer periods as well, as a result of Earth’s changing climate. If cloud and ice coverage goes down, so does Earth’s overall brightness. And several studies have reported that that’s just what’s happening. Earthshine isn’t as bright as it was decades ago. The difference is small but clear – providing slightly darker nights on the Moon. Look for the Moon low in the sky before dawn tomorrow. The bright star Antares, the heart of the scorpion, is close by. Script by Damond Benningfield

Mighty Orion the hunter has a mighty resting spot for his tired feet: Cursa, the second-brightest star of Eridanus, the river. The star’s name comes from a longer Arabic phrase meaning “footstool of the central one” – Orion himself. As night falls, the star stands above Orion’s foot: Rigel, the hunter’s brightest star. Cursa is about 90 light-years away. It’s easy to see from that distance because it’s a giant. It’s several times the size and mass of the Sun, and 45 times the Sun’s brightness. Its classification as a “giant” tells us much more than just its size, though. It also tells us about its stage in life. A giant star has puffed up as a result of changes deep in its heart. It’s burned through the hydrogen in its core to make helium, so it’s moved into a new phase. In the case of Cursa, it’s fusing hydrogen in a thin shell around the core. The shell is quite hot, so it produces a lot of radiation. That pushes on the surrounding layers of gas, causing the star to expand. And that makes it brighter. Today, the surface of Cursa is thousands of degrees hotter than the Sun’s. At that temperature, the star shines almost pure white. As it continues to change, though, Cursa may get even bigger and brighter. But its surface will get cooler. So a bigger Cursa will shine redder – an angry-looking footstool for the hunter. Tomorrow: from giant to supergiant. Script by Damond Benningfield