StarDate

3.4 billion years ago, an asteroid the size of a town slammed into an ocean on Mars. It ripped up the sea floor, blasted rock and water vapor high into the sky, and changed the climate across the entire planet. It also generated a tsunami that raced a thousand miles in every direction, dropping boulders far from the impact site. And the first successful Mars lander, Viking 1, set down amid those boulders in 1976.

That’s the scenario outlined in a recent study. Researchers based their findings on the discovery of a large impact crater hundreds of miles from the landing site, and on computer simulations.

Before Viking touched down, scientists had expected to find smooth volcanic plains at the landing site, in a region known as Chryse Planitia. In fact, the site was chosen in part because engineers wanted a smooth, safe spot for the lander. Instead, Viking’s pictures showed lots of boulders.

The origin of those boulders has been a mystery. The new study provides a possible explanation.

The crater is about 60 miles across. It could have been gouged by an asteroid a few miles in diameter. The blast would have been at least 10,000 times more powerful than the largest H-bomb ever tested — creating a megatsunami on the surface of Mars.

Mars stands high overhead at nightfall, and looks like a bright orange star. It’s not far from a fainter orange light, the star Aldebaran. They set by 2 or 3 a.m.
 

Script by Damond Benningfield

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Storms on the Sun can enhance or create storms here on Earth — from off-season typhoons in the western Pacific to ice storms in northern Canada.

The Sun produces giant magnetic storms. They generate outbursts of particles that can slam into Earth. The storms follow an 11-year cycle. At its peak, dozens of storms can blossom at the same time. At its low point, the Sun can go days or weeks with no storms at all.

Scientists first proposed a link between storms on the Sun and storms on Earth decades ago. Studies since then have supported the idea.

Two recent ones show links with off-season typhoons, and with winter storms in many parts of the globe.

The typhoons are in the western Pacific, near the Philippines and New Guinea. When the Sun is especially active, there’s an increase in the number of off-season typhoons. And they’re more likely to occur right after a solar storm reaches Earth. The Sun may trigger the typhoons by disrupting the circulation in the upper atmosphere.

The other study found a link between solar storms and massive winter non-tropical storms on Earth. In particular, it found that ice storms in Canada either broke out or grew stronger when jolts of solar wind hit Earth. Those blasts may create big waves in the upper atmosphere. The waves then heat lower levels of the atmosphere, triggering a series of events that intensifies storms at the surface — storms on Earth set off by storms on the Sun.
 

Script by Damond Benningfield

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In the rocket business, most of what goes up eventually comes back down. And either direction can be a problem for our planet’s atmosphere.

Studies have shown that rocket exhaust can increase temperatures in the upper atmosphere. That could influence hurricane formation, monsoons, and surface temperatures. It also creates chemical reactions that deplete the protective ozone layer.

And a recent study suggests that spacecraft reentering the atmosphere could cause problems, too.

Much of a spacecraft is made of aluminum. As it burns up in the atmosphere, the aluminum either vaporizes or disintegrates into small particles. The larger particles drop to the surface within hours. But the smaller ones can stay in the upper atmosphere for thousands of years. There, both the particles and the vapor can create chemical reactions that damage the ozone layer or form greenhouse gases, which contribute to global warming.

The number of launches is going way up. There were more than 180 launches last year, carrying about 2,000 satellites — both records. And the year before, more than 300 tons of satellites fell back to Earth. And all of those numbers are expected to keep going up in the years ahead. The new study says if those projections are right, then reentering satellites could add more than 550 tons of aluminum to the upper atmosphere every year. And that could be bad news for our changing environment.
 

Script by Damond Benningfield

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Growing up in the Swiss Alps, Fritz Zwicky liked to throw rocks across rivers, and snowballs at church steeples. He just wanted to throw things higher and farther than anyone else.

Decades later, Zwicky became the first person to throw something away from Earth — a metal ball bearing blasted from the nose cone of a rocket. It escaped Earth’s gravity and went into orbit around the Sun. It was the first step in a grand plan to explore the solar system.

Zwicky was born 125 years ago today, in Bulgaria. After earning his doctorate in astronomy, he joined the Mount Wilson and Palomar observatories in California.

At the time, any star that suddenly flared into view was called a nova. But in the late 1920s, Zwicky realized that not all of these stars are alike. Some are far more powerful than others, so they’re called supernovas. Zwicky and a colleague also realized that a supernova should leave behind a crushed corpse, called a neutron star. The first one was discovered more than 30 years later.

Zwicky also served as research director at Aerojet Engineering. He studied jet engines, solar-powered furnaces, and colonies on the Moon. And he devised a five-step plan for human expansion into space — from “throwing” pellets farther into space, to reworking the planets and moons of the solar system to make them habitable.

The first four steps have all come about. But the last is still a bit more than a stone’s throw into the future.
 

Script by Damond Benningfield

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The Coma Cluster consists of more than a thousand galaxies, all moving through space together. Yet most of the cluster is invisible — it consists of dark matter. It produces no energy, but its gravity pulls on the visible matter around it.

The Coma Cluster provided the earliest evidence of dark matter. It was first suspected by Fritz Zwicky, who was born 125 years ago this week. We’ll have more about him tomorrow.

Zwicky was studying observations of the Coma Cluster made by Edwin Hubble, the namesake of Hubble Space Telescope. He found that many of the galaxies were moving too fast to be held by the gravity of the cluster’s visible matter. He surmised that some form of “dark matter” was contributing to the cluster’s total gravity.

But there were so many uncertainties in the observations that other astronomers didn’t buy it. It wasn’t until the 1970s that enough evidence began to pile up to convince most astronomers.

Today, we know that dark matter makes up about 85 percent of all the matter in the universe. Yet we still don’t know what it is. The leading idea has been that it’s a heavy subatomic particle. But searches have all come up empty. So new searches are focusing on much lighter particles — perhaps the “missing mass” of the universe.

The Coma Cluster is in the constellation Coma Berenices, which climbs into good view in the northeast by 10 or 11 p.m. Small telescopes reveal several of the cluster’s galaxies.
 

Script by Damond Benningfield

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Black holes are everywhere — there could be a hundred million in the Milky Way Galaxy alone. And the closest one yet seen isn’t all that far away — just 1,560 light-years.

Astronomers discovered that one in observations from the Gaia spacecraft. It’s plotting the positions and motions of more than a billion stars. But it’s also making many new discoveries.

One of them is Gaia BH1 — its first black hole. Its images showed a star a lot like the Sun. The star was moving back and forth a bit — likely because of the gravitational pull of a companion. But Gaia didn’t see a companion. Neither did follow-up observations by other telescopes.

The companion had to be a black hole about 10 times the mass of the Sun. It’s probably the remnant of a star that started at about 20 times the Sun’s mass. The star’s core collapsed to form the black hole, while its outer layers blasted into space as a supernova.

The star and black hole are separated by about the same distance as Earth to the Sun. That’s the widest gap between the members of a black-hole binary system yet seen. And that’s a puzzle. Computer models say the two objects should be much closer. So astronomers are working to figure out what’s happening with this nearby black hole.

Gaia BH1 is in Ophiuchus the serpent bearer. The constellation is in the southeast at first light, to the upper left of the Moon. Gaia BH1 is far too faint to see without a telescope.
 

Script by Damond Benningfield

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Most stars die in obscurity. The stars are so far away, and their final acts are so faint, that we never see them. But a year ago today, telescopes saw the death throes of a star that was 12 and a half billion light-years away. The star was ripped apart by a supermassive black hole.

The death was known as a tidal disruption event. Astronomers have seen several of them, but this was by far the most distant. The star was roughly the mass of the Sun. It swung close to a black hole at the heart of a galaxy. The black hole is about five million times the mass of the Sun — about the size of the black hole at the heart of the Milky Way.

The event was named AT2022cmc. It was first seen by an automated telescope that observes the sky at visible wavelengths. It soon was picked up by many more telescopes at many more wavelengths.

As the star approached the black hole, the black hole’s gravity ripped it apart in a blaze of light. About half of the star’s debris was captured by the black hole. It joined a disk of superhot gas around the black hole. The process produced shockwaves that generated X-rays and ultraviolet light.

Some of the material was flung away from the poles of the black hole in high-speed jets of particles and radiation. One of the jets was aimed at Earth, so the star’s death was especially bright — one of the brightest objects astronomers have ever seen.

We’ll talk about another black hole tomorrow.
 

Script by Damond Benningfield

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To the eye alone, Spica looks like a bright blue-white star. But the system is far more complicated. It consists of two massive stars locked in a tight orbit. The stars are so close that they distort each other. The bigger of the two pulses in and out like a beating heart. And even though the system is quite young, one of the stars is nearing the end of its life.

Spica’s main star is 11 or 12 times the mass of the Sun, more than seven times the Sun’s diameter, and more than 20 thousand times its brightness. The other star is a little smaller and fainter, but still impressive.

The official distance between the stars is about 12 million miles. But that’s measured from the centers of the stars. When you figure in the sizes of the stars, the distance is only about half of that — just a few percent of the distance from Earth to the Sun.

At that range, gravity distorts the stars. They puff toward each other, so they’re shaped like eggs. As they orbit each other, the angle at which we see them changes. That causes a small change in Spica’s overall brightness.

The system is only about 12 million years old — a tiny fraction of the Sun’s age. But the bigger star is near the end. In a few million years, it’ll explode as a supernova. After that, it’ll fade away, and Spica will lose much of its luster.

Spica is especially easy to spot tonight. It’s quite close to the Moon as they climb into good view, shortly before midnight.
 

Script by Damond Benningfield

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Beta Monocerotis is one of the most beautiful triple star systems in the heavens — three blue-white points of light that make a skinny triangle. But the system is even more remarkable than it looks. All three of its stars are among the brightest and the most massive in the galaxy.

Two of the stars are roughly six times as massive as the Sun, and more than a thousand times brighter.

The third star probably orbits the other two. But it’s so far that it takes about nine days for its light to cross the vast gulf between them. So astronomers aren’t yet certain that it’s actually tied to them. Either way, it’s the most impressive of the triplets. It’s heavier than the others, and about twice as bright.

Like the Sun, all three stars will end their lives as cosmic embers known as white dwarfs. But they’ll get there a lot faster than the Sun. Heavier stars use up their nuclear fuel more quickly, so they live shorter lives. The stars of Beta Monocerotis will live less than one percent as long as the Sun before they enter the final phases of life. For a short while, before they become white dwarfs, each of them will shine much brighter than it is today.

For now, look for Beta Monocerotis in the southeast at nightfall. Although it’s the brightest star of Monoceros, the unicorn, it’s quite faint, so you need dark skies to see it. But it’s to the lower left of Orion’s Belt, so there’s a prominent marker to point the way.
 

Script by Damond Benningfield

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Until the 17th century, European skywatchers largely ignored the area to the east of Orion. And it’s hard to blame them — that expanse of sky looks pretty empty.

By the early 1600s, though, things were changing. For one thing, European powers were exploring the world’s oceans, so navigators began producing more detailed maps of the sky. And for another, as astronomers turned their early telescopes toward the sky, they found that many “empty” regions were actually filled with amazing sights.

So 400 years ago, a new constellation was created to encompass a dark area near Orion: Monoceros, the unicorn. It’s still not much to look at with the eye alone. But a telescope reveals a triple-star system, a star that staged a big outburst, and much more.

Perhaps the most famous of the unicorn’s wonders is the Rosette Nebula, a giant cloud of gas and dust that surrounds a cluster of young stars. Through a telescope, it looks like a faint smudge of light. But in photographs, it looks like an orange or pink rose — a beautiful decoration for a faint unicorn.

To find the unicorn, first find Orion, which wheels across the south in early evening. Sirius, the brightest star in the night sky, is below Orion, with fainter Procyon farther to the hunter’s lower left. The unicorn fills the space between these bright lights — a region of the sky that’s best appreciated with a telescope.

We’ll have more about the unicorn tomorrow.
 

Script by Damond Benningfield

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