StarDate

A big research telescope is never finished. Over the decades, it can be upgraded with new optics, better pointing systems, and new instruments for capturing the light from astronomical objects. So instead of getting weaker as time goes on, it gets better.

A case in point is the Hobby-Eberly Telescope at McDonald Observatory. It’s one of the biggest telescopes in the world. Its main mirror, which gathers and focuses starlight, is three stories tall.

HET was dedicated two decades ago. But after a multi-year upgrade, it was re-dedicated in April. McDonald director Taft Armandroff explained some of the changes:

HET has been upgraded to a wider field, with better image quality and truly remarkable instrumentation to attack the scientific problems that our scientists have deemed our top priority. In fact, we have some of the most complex and ambitious astronomical instrumentation on the planet right here in our back yard now.

More new instruments are being installed and tested this summer and fall.

Astronomers will use these new instruments to look for dark energy, which is causing the universe to expand faster as it ages. They’ll also hunt for planets in other star systems, and try to learn about the planets they discover. And they’ll study the properties of stars, the way galaxies cluster together, and much more.

The astronomers also will be using an even bigger telescope that’s under construction in Chile. More about the Giant Magellan Telescope tomorrow.

Script by Damond Benningfield

You have to get up pretty early at this time of year to enjoy the beauty of the pre-dawn sky. If you happen to be up, though, it’s well worth a look. That’s because the eastern sky offers up the same stars that’ll decorate the evening sky come winter — some of the brightest and most beautiful stars and constellations of them all.

It also offers a bonus: Venus, the brilliant “morning star.” It’s low in the east at the first blush of twilight. There’s nothing else even close to its brilliance, so you won’t have any trouble picking it out.

The constellation Orion perches off to its right, with bright orange Betelgeuse even with Venus. Orion’s other major features stretch to the right of Betelgeuse: Orion’s three-star belt, which points up and down as it rises, and blue-white Rigel, the hunter’s brightest star.

The twins of Gemini hunker to the lower left of Venus, with Castor a little above brighter Pollux.

Brilliant Capella stands far above the twins, outshining all the other stars in that region of the sky. And Taurus, the bull, is high above Orion, marked by his bright orange eye, the star Aldebaran, and by the twinkly little Pleiades star cluster at his shoulder.

All of these stars rise four minutes earlier each day. So by the time we reach the start of winter, they’ll be climbing into view not at the end of the night, as they are now, but at its beginning — kicking off some long, cold nights under the stars.

Tomorrow: back in action.

Script by Damond Benningfield

The Dog Star is just beginning to emerge from the Sun’s glare in the dawn sky. According to tradition, that means we’re just getting into the Dog Days of summer.

Sirius is the brightest star in the night sky. It’s climbing into view in the morning glow of the brightest star in all the sky — the Sun. Sirius is quite low in the east-southeast shortly before sunrise. It’s best seen from the southern tier of states, although it’ll pull into better view from the northern states over the coming days and weeks.

Sirius is also the leading light of the constellation Canis Major, the big dog, so it’s known as the Dog Star. And that’s where we get the name for this part of summer — the Dog Days.

Sirius makes its closest approach to the Sun in our sky during the summer, disappearing for a few weeks in the Sun’s glare. In ancient times, it returned to view in the morning by early July — just as the weather was reaching its hottest. At the time, it seemed logical to associate the bright star with the sweltering weather. So the people of ancient Greece and Rome named the period of the year after Sirius returned to view in the star’s honor.

Thanks to an effect known as precession, over the centuries the stars shift position with respect to the Sun. So Sirius now returns to view a few weeks later than it did thousands of years ago. So the heat is in full force at northern latitudes — the Dog Days of summer.

Tomorrow: Winter skywatching at daybreak.

Script by Damond Benningfield

The star Mu Andromeda is bigger, heavier, and brighter than the Sun. That extra kick makes it visible to the unaided eye, even though it’s 130 light-years away.

The star also produces some odd radio signals. In fact, they’re among the most interesting picked up in the first year of Breakthrough Listen — a project that’s looking for signals from extraterrestrial civilizations.

The project is using radio telescopes in West Virginia and Australia. Earlier this year, it reported its observations of almost 700 stars. Each star was observed in one band of radio waves, with three scans of five minutes each.

The project recorded millions of radio “hits.” Almost all of them came from interference here on Earth. Only 11 stars produced radio signals that were considered “significant.” But none of them is thought to be a message from ET — they’re most likely odd signals from the stars or their environments.

Those initial results analyzed only a fraction of the observations obtained during Breakthrough Listen’s first year. The project’s going to run for a decade, and it recently teamed up with another radio telescope, in England. So it’ll take a long time to sift through all the data to see if another civilization is on the air.

Mu Andromeda is the brightest of the “significant” stars. It climbs into view in the northeast by around 11 p.m., above Mirach, Andromeda’s second-brightest star. Under fairly dark skies, it’s easy to pick out.

Script by Damond Benningfield

William Pickering was supposed to be studying the stars. By the summer of 1892, he’d set up an observatory in the Andes Mountains of Peru to photograph southern skies for Harvard College Observatory. Instead of the stars, though, Pickering was mesmerized by a different orb: the planet Mars. That summer it was passing especially close to Earth, so it was big and bright — a beautiful sight through a telescope.

So Pickering watched and sketched Mars every night for more than two months. And he reported his findings to a newspaper. He sent regular cables to the New York Herald, which were picked up by other papers around the world.

And the reports were sensational. Pickering confirmed that Mars was crisscrossed by canals. He counted 40 lakes, and reported seeing snow coat mountain ranges, then melt and pool between them. And he monitored what he thought were areas of vegetation.

None of that was well received by Harvard Observatory’s director — Pickering’s brother, Edward, who scolded William for his reports. Edward had already relieved William of his post effective at the end of 1892, and the Mars telegrams didn’t help William’s case.

William later went to Jamaica, where he continued to monitor Mars — convinced of the reality of the canals.

Alas, the canals were just illusions, perhaps enhanced by the belief that they existed. Mars was cold, dry, and desolate — a dead world that captured the public imagination 125 years ago.

Script by Damond Benningfield

Mars is hidden from view right now. It’s looping behind the Sun, so it’s lost in the Sun’s glare. It will return to view in late September, in the dawn sky.

But 125 years ago this month, it was a different story. Mars was putting on a brilliant show as it passed just 35 million miles from Earth — an especially close encounter. And astronomers took advantage of the alignment to study the Red Planet in detail.

In particular, many of them were trying to see the famous “canals” reported 15 years earlier by Giovanni Schiaparelli. The Italian astronomer had drawn a map of Mars that showed an entire network of straight lines crisscrossing the surface. Schiaparelli opined that they were river channels carved as Mars evolved. But others thought they were artificial features — irrigation canals dug to carry water to a dying civilization.

Photography wasn’t good enough in 1892 to take sharp pictures of the planet. So the astronomers had to sketch what they saw through their telescopes. Some of them confirmed the canals, although many others did not.

One confirmation came from Peru, where William Pickering was operating a mountaintop observatory for Harvard College. He saw many amazing sights on Mars, such as lakes and fresh snowfalls on mountaintops. He reported those findings in dispatches to the New York Herald — reports that caused a worldwide sensation, but didn’t do Pickering’s career any good at all. We’ll have more about that tomorrow.

Script by Damond Benningfield

If you put a bottle of water in your freezer and leave it for a few hours, it’s likely to shatter. That’s because, unlike other liquids, water expands when it freezes.

One of the moons of Saturn may have cracked for the same reason — water inside the moon froze, expanded, and created a crack that goes almost three-quarters of the way around the moon.

Tethys is about 650 miles in diameter — less than a third the size of our own moon. It’s made mainly of ice.

Long ago, a big asteroid or a small moon slammed into its surface, blasting out a huge crater, known as Odysseus. The crater is so big that the impact probably would have pulverized a solid body. The fact that Tethys survived the collision suggests that it had a liquid or slushy interior when it was hit.

That liquid most likely was water. Tethys is so small, though, that it quickly lost its internal heat, so the water froze. As the ice expanded, it may have cracked the crust from pole to pole, creating the massive canyon known as Ithaca Chasma. It’s up to 60 miles wide and three miles deep.

It’s also possible that the canyon was created by shockwaves from the impact that carved Odysseus crater. But the two features appear to be different ages, lending credence to the idea that Ithaca formed as water froze inside this icy moon.

And Saturn is quite close to our own moon tonight. The giant planet looks like a bright star just to the lower left of the Moon at nightfall.

Script by Damond Benningfield

We don’t know when or even if we’ll return to the Moon. And we certainly don’t know if we’ll ever build colonies there. But space agencies are laying the groundwork for such missions. Scientists in Europe, for example, are developing possible small lunar satellites, as well as materials for building permanent habitats on the Moon.

Four teams are spending the summer developing lunar cubesats — cubes about four inches on each side. Although they’re tiny, they can carry sensors that can do big work. And they can be combined to make larger satellites.

Several of these cubesats would support human missions to the Moon. One of them, for example, would monitor radiation at the Moon, which is key to understanding how to survive there. Another would map minerals and ices on the lunar surface; water ice could be an important resource for future colonies. And a third would watch for impacts by space rocks, which could endanger lunar visitors.

Other teams have used 3D printers to make bricks from simulated lunar dirt. The bricks are being tested to see how strong they are and how long they last. If they hold up, they could make it possible to build habitats using lunar materials — whenever that might happen.

And the Moon has two bright companions tonight. The star Antares stands below or to the lower left of the Moon at nightfall. The brighter planet Saturn is a bit farther to the left of the Moon. More about the Moon and Saturn tomorrow.

Script by Damond Benningfield

The celestial swan climbs high across the southern sky on summer nights. It’s marked by its bright tail, the star Deneb, which is the lower left point of the wide-spread Summer Triangle. The swan’s body angles to the upper right of Deneb, as though the swan were taking off from a pond. Its long, graceful wings flank the swan’s body.

The brightest star of the top wing is known as Delta Cygni. It’s a system of at least three stars. Two of them are a good bit bigger, brighter, and heavier than the Sun, while the third is less massive than the Sun.

The two heavier stars orbit each other at an average distance of almost 15 billion miles — roughly 150 times the distance from Earth to the Sun. But the little guy is much farther out.

It’s possible that when the system was born, the third star was closer in. But as the stars danced their complex orbital ballet, they swapped some of their energy. The lightweight star was pushed outward, while the heavier stars spiraled closer together.

Those stars were pushed into a stretched-out orbit that looks a bit like an oval racetrack. It takes the two stars almost eight centuries to complete one lap around that track. But the lonely third member of the trio needs a bit longer. It takes many thousands of years to orbit its brighter companions.

Look for Delta Cygni above Deneb as darkness falls. It’s about a third of the way up from Deneb to brilliant Vega, the brightest member of the Summer Triangle.

Script by Damond Benningfield

The celestial scorpion curves above the southern horizon as night falls on summer evenings, with the bright orange star Antares as its bright heart.

Antares is one of the most impressive stars in the galaxy — a supergiant that’s destined to explode as a supernova. But a fainter star that stands close to its right is pretty impressive, too. Sigma Scorpii consists of four stars, at least one of which will also end its life with a giant bang.

Two of Sigma Scorpii’s stars form a tight pair — their surfaces are separated by about half the distance from Earth to the Sun. They’re so close together that even the biggest telescopes see them as a single pinpoint of light. But instruments that break the light into its individual wavelengths detect the presence of two stars, not one.

Both stars are much bigger, brighter, and heavier than the Sun. Their details have proved a bit elusive, but a recent study found that the dominant member of the pair is about 14 times as massive as the Sun and about eight times the Sun’s diameter. Its companion is smaller and lighter, but still a stunner.

The heavier star is almost certain to explode as a supernova sometime in the next few million years. But the companion’s fate is less certain. The star is near the mass limit for a star that will become a supernova. Above that limit, it goes boom. Below it, the star sheds its outer layers, leaving its hot, dense core — a dead star known as a white dwarf.

Script by Damond Benningfield