The evening sky offers up a couple of nice conjunctions tonight. One of them disappears quickly, but the other lingers awhile.

The early pairing is the planets Venus and Mercury. The two worlds are quite low in the west at sunset, and drop from view about the time it gets good and dark.

If you have a clear horizon, though, you should be able to pick them out because Venus is the brilliant “evening star.” It’s far brighter than any of the other planets or stars in the night sky, so it stands out. In fact, the main problem is that you might not realize that it’s a planet — Venus is often mistaken for the landing lights of a distant airplane.

Mercury is directly to the left of Venus, by about the width of your finger held at arm’s length. It’s only about one percent as bright as Venus, so it’s tough to see through the evening twilight. But its proximity to brighter Venus will help you pick it out — and binoculars wouldn’t hurt, either.

Over the next few nights, Mercury will vanish from sight as it drops back toward the Sun. But Venus will climb higher, putting on a better show each night.

The other grouping is the Moon, the star Spica, and the planet Saturn, which is in the south as night falls. Spica is quite close to the upper right of the Moon. Brighter Saturn is farther to the upper left of the Moon. The three bright objects remain close together as they wheel across the southwest over the next few hours.

More about the Moon and Saturn tomorrow.

Script by Damond Benningfield, Copyright 2013

For more skywatching tips, astronomy news, and much more, read StarDate magazine.

It takes a lot of hard work to explore the worlds of our solar system. Over the last five years, for example, scientists have analyzed thousands of pictures of Mercury, the planet closest to the Sun, snapped by the Messenger spacecraft. Those pictures have revealed mountains, canyons, craters, and other features — many of which had never been seen before.

But once you find all those features you have to name them — a job that’s not much easier than the exploration itself.

Before Messenger, the only craft to visit Mercury had seen just half of the planet. Scientists came up with more than a hundred names for the features on that hemisphere. Craters were named for deceased writers, painters, and other artists — a list that included Johannes Brahms, Emily Brontë, and Charles Dickens.

Messenger has seen all of Mercury, revealing many more craters. The list of names for them has included Aaron Copland, Walt Disney, and Alvin Ailey.

Nine more crater names were approved earlier this year. Among others, they honor Estonian novelist Betti Alver, horror writer H.P. Lovecraft, and Hawaiian guitarist Charles Pahinui.

The new additions bring the number of named features on Mercury to more than 400 — with thousands more still nameless.

Mercury is quite low in the west shortly after sunset. It’s faint, but you should be able to find it because it’s just to the upper left of Venus, the “evening star.” The two worlds will stand side by side tomorrow evening.

Script by Damond Benningfield, Copyright 2013

For more skywatching tips, astronomy news, and much more, read StarDate magazine.

The crater Degas displays a bright blue color in this image of Mercury from the MESSENGER spacecraft. The blue material, which has been enhanced in this image, is actually quite dark. The craters on Mercury are named for painters, writers, musicians, and other artists. Earlier this year, the International Astronomical Union approved names for nine more craters. Among others, they honor Estonian novelist Betti Alver, horror writer H.P. Lovecraft, and Hawaiian guitarist Charles Pahinui. [NASA/JHUAPL/Carnegie Inst.-Washington]

Text ©2013 The University of Texas at Austin McDonald Observatory

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RADIO MOSCOW: This is Radio Moscow. Here is a special announcement. For the first time in history, a woman has gone up into outer space. A Soviet citizen, Tereshkova.

Valentina Tereshkova was a 22-year-old textile worker when she decided to take up a hobby — skydiving. She became so good at it that a couple of years later she earned the attention of the Soviet Union’s space program. She was one of five women selected to train for a trip to orbit. And 50 years ago today, she became the only one of them to fly — the first woman in space.

At the time, space travel was a powerful symbol of national prowess, and Soviet Premier Nikita Khruschev was a master of space propaganda. He wanted a woman to fly in space to show the superiority of Soviet people and technology

Tereshkova, who picked the call sign “Seagull,” spent three days in space — more than all six American men who’d flown in space combined. Her flight was part of a Soviet doubleheader — another cosmonaut was already orbiting aboard another capsule. The two briefly passed within three miles of each other.

After returning to Earth, Tereshkova was awarded the Order of Lenin and became a goodwill ambassador. But she never flew in space again. And neither did any other woman for almost 20 years. Today, more than 50 women have flown in space. They’ve commanded space shuttles and the International Space Station, and served as NASA’s chief astronaut. All of them followed the trail blazed by a “seagull” a half-century ago.

Script by Damond Benningfield, Copyright 2013

For more skywatching tips, astronomy news, and much more, read StarDate magazine.

About two dozen satellite galaxies orbit the Milky Way, which is a giant among galaxies. By far the brightest of these satellites is the Large Magellanic Cloud, which is best seen from the southern hemisphere. There’s evidence that it owes some of its luster to galactic thievery: It stole some of its stars from another galaxy.

The Large Magellanic Cloud is about 160,000 light-years from Earth, making it one of our nearest galactic neighbors. It’s only about one-tenth as bright as the Milky Way, and just one-hundredth as heavy. It’s easily visible to the unaided eye — but only from south of about Hawaii or southern Mexico.

Astronomers recently observed aging stars in the Large Magellanic Cloud. They found that about five percent of them did not orbit the galaxy’s center with their peers, suggesting the stars came from elsewhere. And the chemical composition of the wayward stars in the Large Magellanic Cloud matches that of the Small Magellanic Cloud, which is the second-largest satellite galaxy to the Milky Way.

The Small Magellanic Cloud is somewhat farther from us than its larger mate, and the two galaxies are just 75,000 light-years apart. That suggests that they’ve been revolving around each other for billions of years. As a result, the astronomers suspect that the Large Magellanic Cloud’s gravity tore millions of stars away from its galactic neighbor — enhancing its own grandeur at the expense of its smaller sibling.

Script by Ken Croswell, Copyright 2013

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Planets, asteroids, and vast clouds of dust encircle the star Vega in this artist's concept. Recent research shows that two vast rings of debris encircle Vega. One ring resembles the asteroid belt in our own solar system, while the other, which is farther from the star, resembles the Kuiper Belt, a zone of icy objects. Vega is in good view on summer nights as the brightest point of the Summer Triangle. [David Hardy]

Text ©2013 The University of Texas at Austin McDonald Observatory

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The second-brightest star in the northern half of the sky is in great view as we head toward summer. Vega is well up in the east as darkness falls and climbs high overhead later on.

Vega is a bit like a scaled-up version of the Sun — it’s more than twice the Sun’s diameter and mass. And recent research shows that it’s encircled by scaled-up versions of the belts of comets and asteroids that surround the Sun — suggesting that it could have a scaled-up planetary system as well.

Two large space telescopes mapped the debris around Vega in detail — bits of dust, rock, and ice that glow at infrared wavelengths.

By studying the observations, astronomers determined that Vega has a ring of dust and rock that resembles the asteroid belt in our own solar system. They also found that there’s a much larger ring of cold material that’s much farther from Vega. That ring resembles the Kuiper Belt — a broad band of icy comets that’s beyond the orbit of Neptune, the Sun’s most distant planet.

The Vega system is about four times wider than the solar system. But if you scaled up the solar system, those belts of debris would look almost identical.

In the solar system, there are four planets between the Sun and the asteroid belt, and four more between the asteroid belt and the Kuiper Belt. No one has yet found any planets orbiting Vega. But the new observations suggest that planets could be orbiting the star — clearing out wide zones between Vega’s “dusty” belts.

Script by Damond Benningfield, Copyright 2013

For more skywatching tips, astronomy news, and much more, read StarDate magazine.

The brilliant star shining in the eastern sky shortly after sunset tonight is beautiful Vega. It’s the brightest member of the constellation Lyra, and one of the best-known stars in the sky.

Perspective views of VegaDuring the 1980s, Vega achieved even greater fame when a space telescope detected dust orbiting the star, suggesting that it might be giving birth to planets. Because of that, astronomer Carl Sagan chose to make Vega the star in the novel “Contact.” In the novel, a signal from intelligent life is beamed from Vega, but the aliens aren’t native to the star. That’s because, as Sagan well knew, Vega was thought to be much too young to have developed intelligent life on any possible planets.

In recent years, though, astronomers have raised the estimates of Vega’s age. In part, that’s because they've discovered that the star spins fast, which distorts its shape.

A team of observers recently studied Vega with an array of telescopes that are linked together to provide sharp views of the heavens. These observations reveal that Vega is even older than had been thought. By using new models of how rapidly-spinning stars age, the astronomers concluded that Vega is between 625 million and 850 million years old.

That’s still only a fraction as old as the Sun. But when the Sun was that age, Earth may already have hosted primitive life. So when you look at Vega tonight, consider that it may have worlds where life has just begun — a mere 25 light-years away.

More about Vega tomorrow.

Script by Ken Croswell, Copyright 2013

For more skywatching tips, astronomy news, and much more, read StarDate magazine.

With the start of summer just a few days away, the signature star pattern of the season is already in good view. The Summer Triangle is low in the east and northeast as night falls, and climbs high across the sky later on.

The triangle’s points are Vega, Deneb, and Altair. Vega is the brightest and stands highest in the sky during the evening hours. In fact, for those at the middle latitudes of the United States, Vega passes directly overhead in the wee hours of the morning. Deneb is to Vega’s lower left, with Altair farther to its lower right.

The Summer Triangle is the largest “asterism” in the night sky — a group of stars that forms an easy-to-see pattern, but that’s not a constellation. Perhaps the best-known asterism is the Big Dipper, whose stars form part of the constellation Ursa Major, the great bear. Another is the Pleiades star cluster, which is often mistaken for the Little Dipper.

Of course, you can create your own asterisms whenever you want. Just step out under the starry sky any night of the year, give your eyes some time to adjust to the darkness, then let your imagination do the rest. Just as it does when you look at fleecy clouds floating across the daytime sky, your brain will start to create patterns among the stars — from dragons and castles to cars and Angry Birds.

It’s a great way to spend a lazy summer night — dreaming under the stars.

And we’ll talk about the brightest member of the Summer Triangle, Vega, tomorrow.

Script by Damond Benningfield, Copyright 2013

For more skywatching tips, astronomy news, and much more, read StarDate magazine.

There’s a pretty good chance that the young Earth got a “big whack” — it was hit by a body as big as Mars. That spun up Earth’s rotation, and blasted out a huge amount of material, which quickly coalesced to form the Moon.

It’s possible that Venus got a big whack as well. The collision didn’t form a moon — at least not one that’s still around today. But it made Venus spin in the opposite direction from most of the other planets in the solar system.

As seen from above the solar system, Earth and most of the other planets rotate in a counterclockwise direction — the same direction in which they orbit the Sun. Venus also orbits in a counterclockwise direction, but it rotates clockwise.

What’s more, it takes the planet 243 days to complete one turn on its axis. The slow, backward rotation rate means that a “day” on Venus — the interval from one sunrise to the next — lasts 117 Earth days.

There’s no way for Venus to be born that way — the planets should all have been spinning in the same direction. So one possible scenario is that something hit the young planet and either flipped it upside down or caused it to reverse directions — putting a new spin on Earth’s closest planetary neighbor.

And Venus is in good view early this evening. It’s the brilliant “evening star” well to the lower right of the crescent Moon. The much-fainter planet Mercury is a little above Venus. Both worlds set not long after the sky gets good and dark.

Script by Damond Benningfield, Copyright 2013

For more skywatching tips, astronomy news, and much more, read StarDate magazine.