Edwin Hubble gets the credit for discovering that the universe is expanding. But that finding was made possible by work done by Vesto Slipher. He was the first to measure the motions of distant galaxies – the key to Hubble’s discovery. Slipher was born 150 years ago today, in Mulberry, Indiana. He worked on the family farm, and developed an interest in astronomy. A college professor helped him get a job as an assistant at Lowell Observatory in Arizona, where he worked for the next five decades. Slipher studied what were called “spiral nebulae.” It wasn’t certain whether these pinwheels were motes of matter in the Milky Way, or “island universes” of stars outside the Milky Way. Slipher used a technique that splits an object’s light into its individual wavelengths. The object’s motion shifts those wavelengths. Objects that are moving away from us are shifted to longer, redder wavelengths. Slipher found that most of the spirals were moving away from us in a hurry. He suggested the objects were far outside the Milky Way. But he couldn’t prove it because he had no way to measure the distances. Hubble did measure the distances, proving that the spirals are separate galaxies. He then combined Slipher’s observations with his own to show that the farther a galaxy, the faster it was moving. Later, astronomers concluded that the universe is expanding – a finding made possible in large part by Vesto Slipher. Script by Damond Benningfield

There’s nothing in the night sky quite like the Pleiades. The star cluster forms a tiny dipper. Depending on sky conditions and the viewer’s eyesight, anywhere from a half dozen to a dozen stars or more are visible to the naked eye. Its unique visage has made the Pleiades one of the most important sky objects in many cultures. The people of the Andes timed the start of the harvest season to its first appearance in the dawn sky. The Aztec year began at about the same time. In Hawaii, the Pleiades was known as Makali’i. And the year began when Makali’i first appeared in the evening twilight – the middle of November. The year, the new year, and a festival period shared a name: Makahiki. The customs varied from island to island. But they had a lot in common. The celebration lasted for several months. Warfare and most work were banned. Instead, people danced, feasted, played sports, and reconnected with family and friends. And they made offerings to Lono, a god of agriculture, music, and peace. The Pleiades is just climbing into the evening twilight, in the east-northeast, across Hawaii and most of the rest of the country. In some Hawaiian traditions, Makahiki doesn’t begin until the first appearance of the crescent Moon in the west after the Pleiades returns. That’s coming up on the 21st – the start of the new year and the celebration that honors it. Hau’oli makahiki hou! – Happy New Year! Script by Damond Benningfield

The Moon shoots the gap between some bright companions tonight: the planet Jupiter and the star Pollux, the brighter “twin” of Gemini. They climb into good view by about 10:30 or 11, and stand high overhead at dawn tomorrow. Jupiter is the largest planet in the solar system, and it has the most turbulent atmosphere. Hurricane-like storms as big as continents twirl across it. Thunderstorms can produce lightning bolts far more powerful than any on Earth, as recorded by a passing spacecraft. And the storms might produce their own giant hailstones: “mushballs” as big as softballs. The idea was first proposed in 2020. And a study published earlier this year supports it. The study used observations by the Juno spacecraft, which is orbiting Jupiter, along with Hubble Space Telescope and a radio telescope on Earth The study says the mushballs may begin as droplets of frozen water far below the cloud deck. They get caught in updrafts that howl at 200 miles an hour. They’re carried to the tops of the clouds, which can be tens of miles thick. Along the way, the ice mixes with ammonia, forming a slushy liquid. When the balls get heavy enough, they begin to drop. As they descend, they’re coated with fresh ice, giving them a hard shell around a slushy middle – mushballs. The mushballs plunge hundreds of miles below the clouds, where they vaporize – “mushing” into the depths of the giant planet. Script by Damond Benningfield

In the early 20th century, scientists discovered a mysterious new type of radiation. The higher they went, the stronger it became. They realized that it came from beyond Earth. And 100 years ago tomorrow, it got a name: cosmic rays. Nobel Prize winner Robert Millikan had become fascinated by the rays from outer space in the early ’20s. He coined the name “cosmic rays” in a paper about them, which he presented to a meeting on November 9th, 1925. Millikan thought the rays were a form of energy produced by matter that was being born in the space between the stars. Others disagreed, especially Arthur Compton – a future Nobel Prize winner himself. He argued they were subatomic particles racing through the universe at almost the speed of light. Compton was right. Cosmic rays are electrons, protons, or the nuclei of atoms. Most of the ones that hit Earth are produced by the Sun. But others come from far beyond our own solar system – and even from beyond our galaxy. The most energetic ones come from exploding stars, or from the violent regions around black holes. Most of these distant cosmic rays are blocked by the Sun or by Earth’s magnetic field. But a few enter the atmosphere. They strike atoms and molecules in the air, creating “showers” of other particles. If a shower occurs above the right kind of clouds, it can create lightning – a terrestrial light show with an extra-terrestrial origin. Script by Damond Benningfield

Nothing can survive the brutal conditions on the surface of the Moon. But a story that debuted 125 years ago depicted a vast civilization below the surface – a society of insects. First Men in the Moon was written by H.G. Wells. It was published over several months in two magazines – “The Cosmopolitan” in the United States, and “The Strand” in Britain. The first installment appeared in November of 1900. In the story, a man named Bedford befriends a scientist named Cavor who’s invented “cavorite” – a substance that nullifies gravity. He builds a ship and covers it with shutters that are coated in the stuff. Opening and closing the shutters allows the ship to move through space. The two men travel to the Moon, where they’re taken underground by the Selenites. Bedford escapes. Thinking Cavor is dead, he returns to Earth alone. But two years later, Cavor starts beaming messages to Earth. He describes the Moon and its inhabitants in detail. After he tells the Selenite’s leader of Earth’s war-like tendencies, though, he’s cut off – and never heard from again. First Men in the Moon was a hit. It influenced scientists and other fiction writers alike for decades, inspiring more stories, plus efforts to reach the Moon – a world populated only in the imagination. The Moon climbs into good view by about 8 o’clock tonight. Elnath – the second-brightest star of Taurus – is quite close to the Moon’s upper left. Script by Damond Benningfield

The black hole at the heart of the Milky Way is like the monster lurking under your bed. It’s four million times the mass of the Sun, and about 15 million miles across – just waiting to gobble up anything that gets too close. But compared to the black holes in many other galaxies, the one in the Milky Way is less like a monster and more like a dust bunny. The largest ones yet seen are thousands of times bigger. They’re known as ultra-massive black holes. Informally, they’re also called SLABs – stupendously large black holes. Just which one is the biggest is uncertain – it’s hard to measure the mass of something that might be billions of light-years away. A recent candidate is in a structure known as the Cosmic Horseshoe. The gravity of a stupendously large galaxy “warps” the view of a galaxy behind it, creating what looks like a big, blue horseshoe. In a recent study, astronomers combined a couple of techniques to measure the mass of the black hole in the foreground galaxy: 36 billion times the mass of the Sun. Researchers say the combo makes the measurement the most accurate for any candidate for the “biggest black hole” honors. But other black holes could be bigger. The biggest candidate is known as Phoenix A. It could be up to about 25 thousand times the mass of the Milky Way’s black hole. But that number is highly uncertain. So the search for the biggest black hole continues. Script by Damond Benningfield

A Little Red Dot might have a big black hole in its heart. And that’s a bit of a challenge to explain. Little Red Dots are galaxies from the first 1.5 billion years of the universe. The name comes from their appearance – they’re small and red, but they’re especially bright. They don’t appear to have enough stars to make them so bright. So a good bit of their “shininess” could come from giant black holes that are devouring material around them. As they tumble inward, the hot gas, dust, and stars produce enormous amounts of energy. Even so, the black hole in one Little Red Dot is a bit of a puzzler. Led by astronomers at the University of Texas at Austin, a team looked at CAPERS-LRD-z9 with Webb Space Telescope. By measuring the speed of material orbiting the center of the galaxy, the team determined that the black hole is up to 300 million times the mass of the Sun. And that’s where the challenge comes in. The galaxy is so far away that we see it as it looked when the universe was just 500 million years old – three percent of its current age. That makes the black hole the most-distant yet seen. But theories of how such monster black holes form say that half a billion years probably isn’t long enough to make one that big. So theorists have a lot of work to do to explain the giant black hole at the center of a Little Red Dot. More about black holes tomorrow. Script by Damond Benningfield

With the autumn harvest safely stowed away, many people in bygone centuries turned their attention to hunting. And just as the Harvest Moon helped them bring in the crops, the Hunter’s Moon helped them find game. The moonlight made it easier to track animals through the empty fields and beyond. Although most present-day Americans don’t have to worry about storing food for the winter, we still keep the names for those full Moons. We had the Harvest Moon last month. And tonight, it’s time for the Hunter’s Moon. The names for both of these full Moons come mainly from parts of Europe and the British Isles. The names were recorded as far back as the early 1700s, but they’d probably been in everyday use for much longer. Variations of the “Hunter’s Moon” label were used by several native tribes and nations in the Americas as well. The Harvest Moon is usually defined as the full Moon closest to the autumn equinox. Most years, that puts it in September. But this year, October’s full Moon edged out September by just a few hours. So the Hunter’s Moon got bumped into November. Officially, the Moon will be full at 7:19 a.m. Central Standard Time tomorrow. So it will appear almost as “full” when it rises tomorrow night as it does tonight – extra time to appreciate the brilliant glow of the Hunter’s Moon. Tomorrow: A giant black hole at the center of a little red dot. Script by Damond Benningfield

In 1908, a space rock the size of a small office building exploded above Siberia, flattening hundreds of square miles of forest. In 1975, several “fireballs” blazed across the night, and instruments on the Moon recorded several impacts. And 30 years later, scientists saw an impact on the Moon. These events might all be related to the Taurid meteor shower, which is underway now. The shower is created by two objects – a comet and an asteroid. They might be the remnants of a larger body that broke apart thousands of years ago. The debris might include larger rocks ranging from the size of boulders to mountains. The material is spaced across a long, wide path. Earth flies through this path twice a year. We sweep up some of the debris – mostly small bits of dust and rock. The amount of material varies from year to year, depending on which part of the stream we pass through. Right now, we’re in a thin region. In 1975, we passed through a denser part, producing more fireballs. It’s been suggested that when we pass through denser parts of the stream, we might encounter some of the bigger rocks, which could cause major damage if they hit us. Astronomers will be watching during the next crossings through dense regions, in the next decade. For now, the Taurids are at their best the next few nights. The Moon will wash out almost all the meteors. But a few fireballs might shine through. Script by Damond Benningfield

The Taurid meteor shower has a double identity. It’s split into two different streams, which peak a few nights apart in early November. Neither stream is particularly impressive, but things pick up when they overlap. Their story begins thousands of years ago, with the breakup of a big ball of ice and dust – Comet Encke. The biggest remaining chunk kept that name. But the breakup created several other big pieces, plus clouds of dust. The whole messy bunch is known as the Encke Complex. The southern Taurid stream consists of small bits of dust and rock shed by Encke itself. The northern stream is produced by one of its offspring – an asteroid that wasn’t discovered until 2004. Both streams contain a lot of debris, but it’s spread across tens of millions of miles. So it takes Earth weeks to fly through the streams. That means the twin showers last a long time, but they’re not usually all that noteworthy – at best, they produce no more than a handful of meteors per hour. Things are a little busier when the showers overlap, as they’re doing now. Unfortunately, the Moon will be full in a couple of days, so it’ll overpower almost all of the Taurids. The streams do produce a few especially bright meteors, but that’s about the best we can expect from the shower with a dual identity. The Taurid Complex may include some especially big, dangerous chunks of debris, and we’ll talk about that tomorrow. Script by Damond Benningfield