StarDate

The solar system is undergoing a population explosion. It’s not adding new members — they’ve been here all along. But astronomers are finding more of them.

Almost all of the newly counted are small chunks of rock and ice. Most are in the asteroid belt — a band of rocky debris between Mars and Jupiter. Astronomers are actually searching for bodies that come close to Earth — potential threats to our planet. But they also catch asteroids that are farther away. So they typically discover thousands of them every month.

They also discover asteroids that are inside Earth’s orbit. Three new ones were announced in October. One of them is the closest asteroid to the Sun yet seen. The orbit of another one crosses ours, so it could someday threaten our planet. The object is about a mile wide, so any impact would be catastrophic.

We won’t have that problem with another recent set of discoveries.

A year ago, astronomers reported more than 450 new objects in the Kuiper Belt — a region beyond the orbit of Neptune, the Sun’s most remote major planet. Some of them follow orbits that average more than 200 times Earth’s distance from the Sun.

The orbits of some of them may be influenced by the gravity of Planet Nine — a suspected giant world deep in the Kuiper Belt. So scientists are studying the orbits to help track down the elusive planet — perhaps adding one more body to the solar system’s growing population.
 

Script by Damond Benningfield

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When most people look at the glass plates preserved at Harvard College Observatory, they see black dots, smears, and smudges. Astronomers see a chance to learn how the stars, galaxies, and clouds those markings represent have changed over the past century or longer. And artists see the beauty of the universe and the hard work of the women who analyzed the plates.

The original plates are negatives — they show the stars in black and the background sky in white. At Harvard, women “computers” marked and labeled the astronomical objects in the images. They also measured the brightness of those objects and made many other notations.

The plates have been scanned to make it easier for astronomers to find them. As part of that process, the hand-made notations were erased, although all of the plates were photographed first, and some of the originals have been preserved.

To commemorate the work of the women computers, artist Erika Blumenfeld created “Tracing Luminaries.” It’s a set of six prints. She erased the stars, leaving only the written notations, which were hand-layered with 24-karat gold.

Lia Halloran interpreted the plates themselves in “Your Body is a Space that Sees.” It’s a series of prints depicting comets, galaxies, and other objects. The titles include the names of the women computers, including Henrietta Leavitt and Annie Jump Cannon — two of the most important astronomers of the 20th century.
 

Script by Damond Benningfield

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Virgo is a popular location for exoplanets, including the first ones ever confirmed. There’s no special reason for it, except perhaps for the size of the constellation — it’s the largest member of the zodiac.

Virgo is easy to find in the wee hours of tomorrow because the Moon passes near Spica, its brightest star.

As far as we know, Spica doesn’t have planets of its own. And if it does, they’re doomed, because the system’s main star will explode as a supernova in a few million years.

There’s no reason an exploded star couldn’t acquire planets after its demise, though. In fact, that may be the case for the first exoplanets ever discovered. They orbit a pulsar — the ultra-dense corpse of a supernova.

The system is near Virgo’s northern border, far from Spica. The pulsar may have formed from the merger of two other stellar corpses, known as white dwarfs. The collision splashed debris into space. Some of that debris may have coalesced to form a system of at least three planets. The first two were discovered in 1992.

Virgo also hosts lots of planets around stars that are still in the prime of life. That includes the star 70 Virginis. Its planet was one of two announced in early 1996, a few months after the discovery of the first such planet. The planet is more massive than Jupiter, the giant of our own solar system. And it’s quite close to the star, so it’s classified as a “hot Jupiter” — one of the many worlds in the constellation Virgo.
 

Script by Damond Benningfield

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A black hole is completely black — it produces no energy at all. Yet its birth may be among the brightest events in the universe. In fact, astronomers saw such an outburst on October 9th, and it was astonishing. One astronomer tweeted that it was “stupidly really bright.” And a group of astronomers nicknamed it the BOAT — Brightest of All Time.

The event was a gamma-ray burst — a flare of the most powerful form of energy. It came from a galaxy about 2.4 billion light-years away. The galaxy is especially dusty, suggesting that it’s giving birth to a lot of new stars.

Some of those stars are especially hot and massive. They burn out in just a few million years, then explode. The extreme conditions inside the exploding star create jets of X-rays and gamma-rays. They tunnel out through the star’s poles, then beam into space. And that’s what astronomers say probably happened with the October 9th event.

If Earth aligns along one of those beams, we see it as a gamma-ray burst. We also feel it. It zapped Earth’s upper atmosphere, interfering with some radio communications. It even created mild electric currents in the ground.

Astronomers continue to keep an eye on the object as it fades away. They’re not sure just how bright it was. But they estimate that, in a few seconds, it produced a thousand to ten thousand times as much energy as the Sun will generate in its entire lifetime — making the outburst the BOAT: the brightest of all time.
 

Script by Damond Benningfield

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A South Korean spacecraft is scheduled to enter orbit around the Moon tomorrow. That will make South Korea the seventh nation or group of nations to successfully reach the Moon. And the mission will lead what’s expected to be a rush on the Moon over the next few years.

Danuri — a smash-up of words that mean “Moon” and “enjoy” — was launched in August. It followed a looping path to the Moon that took more time but less energy. It’ll spend a couple of weeks refining its orbit, then get to work in January.

Danuri is intended mainly as a test flight. It’ll help the Korean space program develop the tools and experience for more ambitious missions later on.

But it also carries a suite of instruments. They’ll map the contours of the lunar surface, study the Moon’s interior, and photograph possible landing sites. An American-built instrument will look into dark craters at the poles for evidence of water ice — a potential resource for future explorers.

Many other craft are supposed to head for the Moon over the next couple of years. The next American mission could launch as early as the next few weeks. It’s part of a NASA program that will use commercial spacecraft to ferry science instruments to the Moon. The program will include a rover to explore the icy craters near the south pole.

China, Russia, India, and several other countries have announced plans for missions as well — beginning a new rush to the Moon.
 

Script by Damond Benningfield

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Our first foray beyond Earth came to an end 50 years ago today. After three days in the Taurus-Littrow valley, Apollo 17 astronauts Gene Cernan and Jack Schmitt headed to lunar orbit. They’d join crewmate Ron Evans for the long voyage home.

At the time, it was clear that it would be a while before people returned to the Moon. But few expected it to take quite this long.

NASA had planned three more Apollo missions. Each would aim at a challenging landing site with high scientific interest. But they were cancelled, either for budget reasons or to use the hardware for other projects.

Over the following decades, NASA considered many ideas for follow-up missions. None of them ever took off.

Today, though, the space agency says it’s about ready to go back to the Moon with its Artemis program. It says astronauts could land on the Moon as early as 2025. But the program is way behind schedule and over budget. And one NASA review said 2025 isn’t a realistic goal.

Still, it seems likely that people will follow in the footsteps of Cernan, Schmitt, and the 10 other Apollo moonwalkers within the next few years.

Shortly before he stepped off the Moon for the final time, Apollo 17 commander Gene Cernan had a few words for those future moonwalkers:

CERNAN: And as we leave the Moon and Taurus-Littrow, we leave as we came and, God willing, as we shall return: with peace and hope for all mankind.
 

Script by Damond Benningfield

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While exploring the gray lunar landscape 50 years ago this week, the crew of Apollo 17 saw something amazing:

SCHMITT: There is orange soil! It’s all over! Orange! Fantastic, sports fans. CERNAN: How can there be orange soil on the Moon?

Geologists wondered the same thing. So Jack Schmitt and Gene Cernan brought some of it to Earth for study. Scientists found the orange came from beads of volcanic glass, probably blasted from a big eruption more than 3.6 billion years ago.

In 2011, scientists looked at the samples again, using tools that weren’t available when Apollo 17 ended. They found that the beads contained a lot of water — the same percentage found in Earth’s mantle — the layer below the crust. It suggests that, even though the lunar surface is dry, the Moon’s insides could’ve had as high a concentration of water as the interior of Earth.

Scientists aren’t through with the Apollo 17 samples yet. They just opened some of them this year for the very first time. The samples had been stored in pristine condition, awaiting the development of new tools — perhaps leading to more discoveries from a 50-year-old mission.

The Moon climbs into good view by 11 p.m. About two-thirds of the hemisphere that faces our way is in daylight, so it’s nice and bright. Regulus, the lead star of Leo, rises to the lower right of the Moon, and is below the Moon at first light.

More about Apollo 17 tomorrow.
 

Script by Damond Benningfield

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It’s hard to think of something that’s moving at 80,000 miles per hour as slow. But that’s the case for Geminid meteors. The bits of rock that create the meteors are a good bit slower than those that form most other showers. And that’s good for skywatchers — it means the meteors last a little longer than most others.

The Geminids are expected to be at their best tomorrow night, peaking before dawn on Wednesday. Unfortunately, the Moon will be in view then, washing out the fainter meteors. But many of the Geminids are fairly bright, so the shower is worth a look.

Geminids are spawned by what appears to be a dead comet. It’s lost its ices, leaving only a rocky core. So it doesn’t produce a tail when it gets close to the Sun, as active comets do. But it does shed grains of material along its orbit. Earth flies through this path every December.

Or at least it does now. The shower was first seen in 1862, with not many “shooting stars.” The rate has gone up since then. So today, the Geminids produce one of the best showers of the year — 75 to a hundred meteors per hour. But that’s under especially dark skies, with no moonlight to mess with the show.

By the way, the shower’s name comes from the constellation Gemini. That’s the point where the meteors appear to “rain” into the atmosphere. But they can streak across any portion of the sky, so you don’t have to look toward Gemini to see these bright slowpokes.
 

Script by Damond Benningfield

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APOLLO 17: And there it is Houston, there’s Camelot! Right on target! I see it! 38 degrees. MISSION CONTROL: Challenger, you’re go for landing. APOLLO: 5,000 feet.

50 years ago today, Gene Cernan and Jack Schmitt were heading for the Moon. The Apollo 17 astronauts guided their lunar module, Challenger, toward a valley in the highlands — a mountainous region in one of the light-colored areas we see on the lunar disk.

APOLLO: Stand by for touchdown. Stand by!

It was the last of the six lunar landing missions of the Apollo program.

APOLLO: Ten feet. Contact! Okay, Houston, the Challenger has landed! MCC: Roger, Challenger. That’s super. APOLLO: Boy, you bet it is Gordo. Oh, man! Look at that rock out there. Absolutely incredible. Absolutely incredible. The epic moment of my life.

Over the next three days, Cernan and Schmitt made three moonwalks. Using a battery-powered rover, they ventured almost five miles from their lander. And they gathered 250 pounds of samples.

Some of the most exciting samples came from a patch of bright orange dirt, which decades later was found to contain water — one piece of evidence that the Moon is much wetter than anyone had expected during the Apollo days.

Some other samples remained untouched until just a couple of years ago. They’d been sealed to avoid contamination. They were opened up to allow scientists to study them with tools and techniques that didn’t exist when Apollo 17 brought them to Earth — a half-century ago.

More tomorrow.
 

Script by Damond Benningfield

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The final Apollo mission arrived at the Moon 50 years ago today, as commander Gene Cernan reported from the command module, America: Houston, this is America, you can breathe easier. America has arrived on station for the challenge ahead.

Apollo 17 was ambitious. Cernan and Jack Schmitt, a geologist, would spend three days on the Moon, in a valley known as Taurus-Littrow. It was picked because scientists thought it would give them a chance to sample two kinds of lunar terrain. One was the older material that forms the lunar highlands — the bright regions you see when you look at the Moon. The other was younger material produced by molten rock bubbling to the surface.

Cernan was a veteran of two space flights. Schmitt had never flown before. He was added to the mission when NASA cancelled his flight, Apollo 18. That made him the first and only trained scientist to walk on the Moon. Crewmate Ronald Evans, also a space rookie, remained in orbit. He operated cameras and other instruments that studied the Moon below.

The rocket firing that put them in lunar orbit went perfectly. And soon afterward, Schmitt reported something odd — the mission’s first bit of science: Hey, I just saw a flash on the lunar surface. MISSION CONTROL: Oh, yeah? SCHMITT: It was a bright little flash.

Scientists weren’t sure if the flash was caused by the impact of a small space rock or an eruption from the Moon itself.

Cernan and Schmitt landed the next day; more about that tomorrow.
 

Script by Damond Benningfield

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