StarDate

Making planets like Earth is a messy business. Bits of dust and rock stick together to make giant boulders. The boulders sometimes ram together, blasting themselves to bits. And the broken bits can then stick together again to form larger bodies.

An example of that process is seen in a young star system in the southern constellation Vela.

NGC 2547-ID8 is in a star cluster that’s 1200 light-years from Earth. The cluster is only about 35 million years old, so its stars — and their planets — are still taking shape.

In recent years, a space telescope has seen a couple of big events in ID8. Both events resulted in a huge jump in the star’s infrared light — an indication that there was a huge infusion of new dust grains.

The first was seen seven years ago this week. Two large asteroids probably slammed together. That ripped both of them to shreds. The impact occurred at about the same distance from the star as Mercury is from the Sun — prime real estate for making rocky planets.

A second pulse of dust was seen in early 2014. Astronomers say that one probably was caused by the first. A big chunk of debris from the initial impact spiraled closer to the star, where it hit another asteroid.

This process adds lots of bits of dust and rock to the disk of debris around the star. These materials can stick together to form larger bodies — asteroids like those that collided, or planets — the result of the messy process of giving birth to new worlds.

Script by Damond Benningfield

Red dwarfs are the smallest and faintest of all stars — so faint that not a single one is visible to the eye alone. Yet they’re also the most common stars. So they’re the targets of several searches for planets.

Red dwarfs would be tough environments for the development of life, though. They’re so feeble that the range of distances where temperatures would be comfortable for life is quite small. The stars produce intense outbursts of X-rays that could destroy a planet’s atmosphere. And at least one red dwarf has been found to fire possible blobs of hot gas.

AU Microscopii is in Microscopium, a faint constellation that’s low in the south at nightfall.

The newborn star is about a third as massive as the Sun. It’s encircled by a disk of dust that could provide the raw materials for making planets.

The blobs are a problem, though. Each one is hundreds of millions of miles across. It may be an explosion of gas from the surface of AU Microscopii.

The blobs are blowing holes in the disk. At the current rate, they could wipe out the entire disk in just one-and-a-half million years. Without the disk, no more planets could take shape. And there would be no comets or asteroids to smack any existing planets — depriving them of sources of water, and perhaps the chemistry of life. So life for a planet — and the development of life itself — might not be easy around a red-dwarf star.

We’ll have more about exoplanets tomorrow.

Script by Damond Benningfield

What happens in the asteroid belt doesn’t necessarily stay in the asteroid belt. In fact, Earth and the Moon might be feeling the effects of actions in the belt hundreds of millions of years ago.

The asteroid belt is a wide band of rocky debris between the orbits of Mars and Jupiter. On average, the big space rocks are widely separated. Every once in a while, though, two of them collide. That can shatter one or both bodies, creating more debris. And if the impact happens at the right location, the debris can skitter toward the inner solar system. Once here, the chips can hit Earth and the Moon, blasting new craters.

A recent study found that the debris from such an asteroid collision might have started bombarding Earth and the Moon almost 300 million years ago.

It’s hard to count the craters on Earth because they’re altered by wind, rain, and the motions of Earth’s crust. But Earth and the Moon get hit by the same wave of material. So researchers counted craters on the Moon. In particular, they looked for craters that were big but young.

They found that the rate of crater formation jumped by a factor of more than two and a half about 290 million years ago. One possible explanation for that is one or more collisions in the asteroid belt — events that are having a big impact on Earth and the Moon.

Look for the Moon high in the sky at first light tomorrow. The bright star Regulus, the heart of the lion, will stand below it.

Script by Damond Benningfield

Fifty years ago, a newborn star flared up — it grew a couple of hundred times brighter. It then faded, although not completely — it’s still several times brighter than it was before the flare-up. And astronomers are trying to figure out why.

V1057 Cygni stands quite close to Deneb, the constellation’s brightest star, which is high overhead at nightfall. Although it’s a hundred times brighter than the Sun, it’s about 1700 light-years away, so it’s visible only through a telescope.

V1057 Cygni is only a few million years old. In fact, it’s still taking shape — it continues to pull in gas and dust from the cloud that’s giving it birth. It appears to be encircled by a disk of gas and dust. And it also appears to be blowing out a strong “wind” of gas from its surface.

The star flared up beginning in 1969. It brightened for a while, then faded much more quickly than other stars of its class.

Astronomers have proposed several possible explanations for the flare-up. One says that the star spins so fast that it’s unstable. It sometimes flings off a lot of gas, causing it to brighten — and to slow down a bit.

Other ideas say that the flare-up came from the encircling disk. And still others say it was caused by interactions with a companion star, or with a giant planet in a close orbit.

Whatever the cause, V1057 is likely to stay busy as it completes the process of its birth — before settling down into a long run in the prime of life.

Script by Damond Benningfield

In the wee hours of October 20th, 1994, Tom Hagon was awakened by two “booms” from above. The first was a sonic boom — the result of a space rock plunging into Earth’s atmosphere. The second was an impact — a chunk of the rock hitting his roof. He dug it out the next morning — a blackened fragment that weighed about a pound.

Space rocks slam into Earth all the time. Back in June, for example, a rock as big as a car exploded above the ocean near Puerto Rico. It was detected by orbiting satellites. Most of the rocks leave no trace. But a few reach the surface. They’ve plunged through roofs, smashed cars, and punched holes in the ground.

The 1994 incident began as a bolide — an especially bright meteor blazing across the sky. It was seen over the Lower Peninsula of Michigan, traveling toward the northeast. It was quite bright. And it created a sonic boom that awakened many from their sleep. The only known fragment landed near the town of Coleman.

After it was recovered from the roof, Hagon donated part of the meteorite for research. Scientists found that it came from the middle of a larger rock — one that weighed up to a couple of hundred pounds before it hit the atmosphere. It was a type of rock known as a chondrite. It formed when dust grains in the early solar system came together and melted. The rock then orbited the Sun, perhaps for billions of years, before it ran into Earth — and a roof in a small town in Michigan.

Script by Damond Benningfield

Earth is running into a celestial sandstorm. We’re plowing into a cloud of dust from Halley’s Comet. That produces a meteor shower — streaks of light across the night sky. Unfortunately, though, the Moon is in the way, so only the brightest of the “shooting stars” will shine through.

This is called the Orionid shower. If you trace the paths of the meteors across the sky, they all converge in the constellation Orion. They can streak across any part of the sky, though, so you don’t have to look at Orion to see them.

The Orionids happen because Earth crosses the path of Halley’s Comet at this time of year. The Sun vaporizes some of the ices on the comet’s surface. As the gases boil into space, they release tiny grains of dirt and rock. Most of these bits are the size of grains of sand or tiny pebbles.

As Earth plows through the comet dust, the particles slam into the atmosphere at up to 150,000 miles per hour.

That extreme speed generates extreme heat, so the particles instantly vaporize — forming meteors. The Orionids aren’t especially bright as meteors go. But they tend to leave glowing trails that remain visible for a few seconds.

The shower should be at its best in the hours before dawn on Tuesday. But it produces some stragglers for weeks before and after that. So if you want to give it a try, find a dark but safe skywatching site, away from city lights. Then scan the sky for Orionid meteors — the result of a cosmic sandblasting.

Script by Damond Benningfield

For a century, astronomers recorded most of their views of the universe on glass plates. By the 1980s, though, the plates were on their way out. They were being replaced by a new technology: the charge-coupled device, or CCD, which was invented 50 years ago this week.

Willard Boyle and George Smith were scientists at Bell Laboratories. They were working on a new type of electronic memory when they created what’s now known as the CCD. They realized the device could be used to take pictures. And within years, CCDs were at the hearts of digital cameras and video recorders.

A CCD takes advantage of the photoelectric effect, in which light can be converted to electrons. It was first described by Albert Einstein, and earned him his only Nobel Prize. Boyle and Smith earned the Nobel for their application of the effect.

Astronomers were among the first to adopt the CCD. The detectors are much more sensitive to light than photographic plates or film. That allows them to see objects that are fainter and farther away. CCDs are easier to use, too, and their images are easier to store and study. And CCDs are good for space telescopes and other craft because they’re lighter and more reliable than earlier electronics.

A CCD was first used on a ground-based telescope in the seventies. Many observatories began switching to the new detectors soon after that. By the end of the century, the takeover was complete — as astronomers cast these new “eyes” on the universe.

Script by Damond Benningfield

All stars are big. But there’s “big” and then there’s big. Consider the Sun and Aldebaran, the “eye” of Taurus, the bull. The Sun is big as stars go — probably in the top 10 percent of all stars. Yet it’s a mere plaything compared to Aldebaran.

The Sun is 865,000 miles in diameter — more than a hundred times the size of Earth. But Aldebaran is more than 40 times that diameter. And when you convert those measurements to three dimensions, the comparison is astounding: Aldebaran is about 85 thousand times the volume of the Sun. To put that in perspective, if the Sun was the size of a green pea, Aldebaran would be bigger than a beachball.

Aldebaran is so much bigger than the Sun because it’s past the end of its “normal” lifetime. Changes in its core have made the core millions of degrees hotter. The extra energy pushes the surrounding layers of gas outward, making Aldebaran puff up to giant proportions.

And it’s not through expanding just yet. Eventually, it’ll get about twice as wide as it is now. After that, though, it’ll quickly slough off its outer layers, leaving only its hot but tiny core — a white dwarf.

The Sun will puff up when it reaches the end of its normal lifetime as well — in several billion years.

In the meantime, look for Aldebaran quite near the Moon tonight. The bright orange star will stand close to the right of the Moon as they climb into good view, around 10 p.m., and a little farther below the Moon at dawn tomorrow.

Script by Damond Benningfield

Most of the stars aren’t alone. But it can be tough to tell which stars have companions. The stars can be so close together that their light blurs into a single point. Or they can be so far apart that it’s hard to confirm that they’re actually bound to each other.

Examples of both can be found in a single star system.

Capella is one of the brightest stars in the night sky. Tonight, it climbs into view in the northeast in mid-evening, far to the left of the Moon.

Capella consists of two pairs of stars that are a trillion miles apart. One pair is quite bright — it forms the pinpoint we see with our eyes alone. The other is too faint to see without a telescope.

The stars that make up the bright pair are separated by about the gap between the Sun and Venus, the second planet out. From our distance of 42 light-years, it takes special telescopes to see the individual stars.

Astronomers discovered their binary nature by breaking their light into its individual wavelengths. That revealed two patterns of light — one for each star. Both stars are bigger, brighter, and heavier than the Sun.

The other pair consists of two faint stellar embers. They’re as far apart as Pluto is from the Sun, so it takes hundreds of years for them to orbit each other. As a result, it took decades to confirm that the stars form a binary. Today, we still haven’t seen them complete even a single orbit. So there’s a bit of uncertainty in the numbers about this faint pair of stars.

Script by Damond Benningfield

A group of scientists and musicians is trying to start a conversation over the back fence. The team sent messages to a star system that’s about 12 light-years away. As stars go, that’s right next door. The first messages went out two years ago tomorrow. So if anybody’s there, and is in a talkative mood, their reply could reach us as early as 2042.

GJ 273 is a red dwarf — a star that’s much smaller and fainter than the Sun. It was picked as a target because it has a planet in the “Goldilocks zone.” That’s the distance from the star where temperatures are just right for liquid water — a key ingredient for life.

Astronomers have beamed signals to a few other stars over the last few decades. But this was the first one aimed at a star that’s known to have a planet that could be habitable.

The message was put together by scientists and by participants in a music festival in Spain. It consists of an interstellar “hello,” along with instructions for deciphering the message — all done with mathematics. It also includes 18 snippets of music, each of which is 10 seconds long.

Everything was beamed into space by a radio telescope in Norway. It took three days to send the whole sequence. More music and math were sent in May of last year — greetings to another star system.

GJ 273 is too faint to see with the eye alone. But it appears quite near Procyon, the brightest star of Canis Minor, the little dog. They’re high in the south-southeast at first light.

Script by Damond Benningfield