StarDate

Hubble Space Telescope entered orbit 30 years ago last week.

LAUNCH CONTROL: 3, 2, 1, and liftoff of the space shuttle Discovery with the Hubble Space Telescope, our window on the universe.

And it’s still going today. Over the decades, it’s provided new insights into stars and galaxies, the age of the universe, and even the future of the universe. But it’s needed some help.

ENDEAVOUR: Endeavour has a firm handshake with Mr. Hubble’s Telescope.

Five crews of shuttle astronauts upgraded its instruments and repaired or replaced ailing systems — the last in 2009.

LAUNCH CONTROL: Liftoff of space shuttle Atlantis on the final visit to enhance the vision of Hubble.

A service call is unusual for missions of exploration, though. Engineers can send commands to overcome some problems, and they can upgrade the computer software, but major failures don’t get fixed.

Even so, several explorers have operated as long as Hubble has — or even longer.

The champions are Voyagers 1 and 2. They were launched in 1977 to explore the outer solar system. They’ve left the solar system behind — they’re studying interstellar space.

They’re losing power, so most of their instruments have been turned off. And they have occasional problems. Voyager 2, for example, went into “safe mode” in late January. It saw that something was wrong, then shut down and waited to hear from Earth. Engineers sent commands to get Voyager started again — keeping this aging explorer going for a little while longer.

Script by Damond Benningfield

It’s definitely not Kansas. But it is home to one of the state’s favorite characters, Dorothy Gale. Captain Nemo is there, too. And so are Arthur C. Clarke and Stanley Kubrick – the creators of “2001: A Space Odyssey.”

Charon is the largest moon of Pluto. It’s about 750 miles in diameter – a third the size of our own moon.

The New Horizons mission gave us our only close look at it in 2015. It found that Charon has a dark orange “beanie” cap – ices that wafted off the surface of Pluto. It has a thousand-mile “belt” of canyons around its equator. And several big impact craters are carved in its icy surface.

The International Astronomical Union has named about a dozen of those features. All of the names are related to exploration – places, writers, or vessels connected with real or imagined lands.

One of the canyons, for example, is Argo Chasma. It’s named for the ship that carried Jason and the Argonauts. It has some of the tallest cliffs in the solar system – up to six miles high. The “beanie cap” is called Mordor Macula, after a character from “Lord of the Rings.” Gases from Pluto form a fresh coating of ice at the north pole. The ice turns orange when in the sunlight. And a mountain is named for Octavia Butler, a science-fiction author.

Many other features are waiting to be named. All of the names will follow the same theme – honoring the spirit of exploration.

We’ll talk about some current explorers tomorrow.

Script by Damond Benningfield

A “mini-Milky Way” arcs low across the south on spring evenings. It’s a galaxy that probably resembles the Milky Way, but it’s only half as big.

Messier 83 is a beautiful spiral that we view face-on. It’s only about 15 million light-years away, so the view is especially good. The galaxy has a “bar” of stars across its middle, with spiral arms extending from the ends of the bar. That appearance has earned it a nickname: the Southern Pinwheel.

Although it’s much smaller and less massive than the Milky Way, M83 is much busier. It’s giving birth to many new stars. Astronomers have discovered about 3,000 star clusters in the galaxy, many of which are less than five million years old. They’ve also discovered the remnants of about 300 massive stars that exploded fairly recently.

All that activity may be the result of a near-collision with another galaxy. The galaxies may have passed near each other a billion years ago. The gravity of each galaxy squeezed clouds of gas and dust in the other galaxy. That caused the clouds to collapse and give birth to new stars — a process that continues today.

M83 is in Hydra, the water-snake. It climbs into view a couple of hours after sunset, and is low in the south around midnight. The galaxy is too faint to see with the eye alone. Binoculars reveal a small, hazy circle of light. Telescopes reveal more detail — a beautiful galaxy pinwheeling across the southern sky.

Script by Damond Benningfield

From the globular star cluster Messier 53, the view would be spectacular. The cluster floats high above the disk of the Milky Way Galaxy. So the entire galaxy would spread out below it — from the graceful spiral arms to the star-packed core.

M53 orbits the core, so it’s a member of the galaxy. But that might not always have been the case. Studies have suggested that it was born in another galaxy — perhaps as the galaxy’s core. Billions of years ago, that galaxy was pulled in by the Milky Way’s powerful gravity. Most of its stars were stripped away and absorbed by the Milky Way’s disk. But M53 stayed in the halo — a vast region that surrounds the disk.

Today, the cluster is perhaps 60,000 light-years from the core — and about the same distance from Earth. But its orbit carries it up to twice as far from the galaxy’s heart.

The view inside the cluster would be spectacular as well. M53 contains hundreds of thousands of stars. Most of them are packed into a ball only a few dozen light-years across. So the night sky of a star inside the system would glow with many more bright stars than our own sky. That would make the view from M53 doubly impressive — stars all around, and the Milky Way below.

Messier 53 is in the constellation Coma Berenices. The cluster is well up in the east at nightfall, and is an easy target for binoculars. It’s easier to see by around midnight, as the Moon drops from view.

Script by Damond Benningfield

Venus is our closest planetary neighbor, and the brightest object in the night sky except the Moon. In fact, you can see them close together tonight. Venus, the “evening star,” is close to the right of the Moon as night falls.

Despite Venus’s dramatic appearance, until spacecraft started exploring it, no one had ever seen its surface. That’s because the entire globe is blanketed by clouds. And without being able to see surface features rotating into and out of view, astronomers couldn’t even measure the length of a Venusian day.

One thing they did know is that Venus rotates backwards from the other planets. While the Sun rises in the east and sets in the west here on Earth, it’s just the opposite on Venus.

Through telescopes, astronomers could see formations in the planet’s clouds. From that, they calculated that the clouds move around the planet every four days.

Finally, in 1961, they used a giant radio telescope to bounce radar signals off the surface of Venus. By measuring a small shift in the returning waves, they found that Venus completes one turn on its axis in 225 Earth days. Because of its backward spin, though, the length of a “day” on Venus — the time from one noon to the next — is about 117 days.

The length of a day doesn’t have much effect on temperatures on Venus, though. The planet’s dense atmosphere locks in heat, so the surface temperature remains about 860 degrees Fahrenheit — day and night.

Script by Damond Benningfield

A couple of bright companions attend the Moon this evening. Aldebaran, the orange eye of Taurus, the bull, stands just to the left of the Moon. And Venus, the brilliant “evening star,” is well above them.

The Moon is a thin crescent right now. That means it’s nighttime for most of the hemisphere that faces our way. It’s daytime only for the bright crescent.

That doesn’t mean it’s fully dark on the lunar nightside, though. In fact, it’s pretty bright. You can see that for yourself as the sky begins to darken. Most of the lunar disk will take on a ghostly appearance – the result of earthshine – the brilliant glow of our home planet.

If you were standing on the Moon, you’d see an almost-full Earth hanging in the sky. Earth is almost four times wider than the Moon, so it’s a much bigger target in the lunar sky than the Moon is in ours. And, on average, Earth reflects about three times more sunlight than the Moon does. The exact number varies depending on cloud cover and which part of Earth you’re looking at. So a full Earth is about 40 times brighter than a full Moon.

And except from the edges of the Moon’s disk, Earth never rises or sets in the lunar sky. That’s because the same side of the Moon always faces our way. So from any point on that hemisphere, Earth always hangs in the same spot. Our planet waxes and wanes but doesn’t move – a constant presence in the lunar sky.

We’ll have more about the Moon and Venus tomorrow.

Script by Damond Benningfield

Telescopes routinely study galaxies that are billions of light-years away. But just a century ago, no one knew that the universe extended that far. While many astronomers were coming around to the concept of a vast universe, many others thought the entire universe was contained inside the Milky Way Galaxy.

Two astronomers outlined these viewpoints 100 years ago Sunday, at a meeting in Washington, D.C. Their discussion is known today as the Great Debate.

Heber Curtis argued that the universe consisted of many galaxies, not just our own. Curtis was 47 years old and worked at Lick Observatory. He and others felt the spiral-shaped objects visible through telescopes were other galaxies as big as the Milky Way. If that were the case, then they’d have to be millions of light-years away.

Curtis also argued that the Milky Way was fairly small, with the Sun at its center.

The other presenter was Harlow Shapley, a 34-year-old at Mount Wilson Observatory. He said the “spiral nebulae” were star clusters on the edge of the Milky Way. But he said the Milky Way was bigger than Curtis’s estimate, with the Sun far from the center.

A few years later, Curtis was proved right about the spiral nebulae — they are other galaxies. But Shapley was right about the Milky Way.

The Great Debate proved to be a dividing line — between old concepts of a small galaxy and universe, and more modern ones where both stretch across vast distances.

Script by Damond Benningfield

The Big Dipper is high in the sky at nightfall at this time of year, with W-shaped Cassiopeia low in the sky. If you look shortly before dawn, though, they’ve moved. The dipper is in the northwest, with Cassiopeia the same height in the northeast.

The stars haven’t moved at all, of course. Instead, they’ve changed position in our sky because Earth is turning on its axis. All the stars appear to revolve around the North Star — the point the axis aims at.

Except for the Sun, Moon, and planets, everything appears to turn together. The stars all maintain their relative positions from night to night, year to year, and even century to century. That unified rotation may have played a role in the name for everything there is: universe.

The word comes from Latin roots that mean “one” and “to turn.” So “universe” can be taken to mean “everything is turning together.” A 19th-century astronomy textbook, in fact, said that was what the word was intended to convey. Earth was a static platform around which everything else turned. Everything beyond Earth belonged to the universe.

A more-modern view of the word’s early meaning is “turned into one.” In other words, everything belongs to a single framework.

And today, universe means “everything there is” — including Earth. Our planet is no longer the hub of everything, but a part of it — bringing new vistas as it spins through the universe.

We’ll talk about a debate over the extent of the universe tomorrow.

Script by Damond Benningfield

Apollo 8 carried the first astronauts to the Moon, at the end of 1968. They orbited the Moon on Christmas Eve and Christmas Day. When they came home, they brought back a lot of close-ups of the lunar surface. But what really caught people’s attention were pictures of Earth — a blue-white marble rising above the stark lunar landscape.

By that time, many people were concerned about our home world. There’d been a series of environmental disasters during the 1960s. And no one seemed to be doing anything about the problem.

Inspired by those problems — and by the Space Age pictures of Earth — activists organized an event for April 22nd, 1970 — 50 years ago today. It became the first Earth Day.

Although the environmental movement was fairly new then, Earth Day was a big success. And it led to some big changes. The Environmental Protection Agency was formed that year. And laws protecting the air, water, and endangered species soon followed.

Earth Day has been celebrated every year since. And this year marks the event’s fiftieth anniversary. The theme is climate change — the problems caused by human activities.

Astronauts may return to the Moon within the next few years. And they’ll snap many more pictures of Earth. But it’s unlikely that any of them will have the same impact as those taken half a century ago — pictures of a “pale blue marble” in the blackness of space.

We’ll talk about everything beyond Earth tomorrow.

Script by Damond Benningfield

The Lyrid meteor shower should be at its best tonight, after midnight. Under dark skies, away from city lights, you might see a few dozen “shooting stars” in all.

The Lyrids are spawned by Comet Thatcher. This ball of ice and rock orbits the Sun once every 415 years. It sheds grains of solid material on each orbit. Earth passes through this trail of debris every April, creating the meteor shower.

Last year, a second shower was taking place at the same time as the Lyrids. It wasn’t much — tracking cameras detected about a dozen meteors. But it suggests that a big comet could be headed our way.

The shower was called the 15-Bootids. It was detected by cameras in Europe and the Middle East. Scientists used images from multiple cameras to plot the paths of these meteors. That allowed them to trace their original orbits around the Sun.

From that, the scientists found that the bits of debris might have come from a bright comet that last visited the inner solar system in the year 539.

The speed of the meteors suggests the comet is big — perhaps 10 miles in diameter. Because its trail crosses Earth’s orbit, it could be a threat to hit our planet. And the presence of the shower suggests the comet could be getting close.

The 15-Bootid shower isn’t expected to be seen again until 2027. In the meantime, though, check out the Lyrids. Find a dark, safe skywatching location, far from city lights, and look up — for fireworks from a comet.

Script by Damond Benningfield