StarDate

One of the most beautiful astronomical conjunctions you’ll ever see decorates the dawn sky tomorrow. The Moon will team up with the planets Venus and Jupiter, the second- and third-brightest objects in the night sky. All three will remain visible for a good while as twilight begins to paint the sky. And two of the three will stay visible even during full daylight.

The Moon is fairly easy to spot, even though it’s only a thin crescent. At sunrise, it’ll stand about 40 degrees to the upper right of the Sun — four times the width of your fist held at arm’s length. Against the bright blue of the daytime sky, it looks pale and washed out — a mere shadow of its nighttime appearance. So you have to search for it to see it.

The same thing applies to Venus. Before daylight, it’s the brilliant “morning star.” It’s so bright that people often mistake it for an airplane, or report it as a UFO. During the day, though, it doesn’t stand out at all — you have to work to pluck it from the glare. At sunrise, it’ll be a little to the upper right of the Moon. Once you lock in, though, you’ll probably wonder why it took so long to find it.

And if you have binoculars, you can even catch nearby Jupiter shining faintly against the blue background.

Venus and Jupiter are moving closer together, and will appear to almost touch each other in a few days — especially pleasing before the Sun floods the sky with the light of another day.
 

Script by Damond Benningfield

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The Moon is continuing to run the gauntlet of planets in the early morning sky. Over the next couple of days it’ll team up with the two brightest planets of all, Venus and Jupiter. They’ll stand close to the left of the Moon at first light tomorrow, and just above the Moon on Wednesday. Fainter Mars will stand to their upper right, with Saturn farther still.

Venus is the brightest of the four planets. Its brilliant appearance is the result of its closeness to Earth and the Sun, and to the bright clouds that completely blanket the planet. The clouds are made mainly of sulfuric acid, which makes it tougher for spacecraft to drop through them. Several probes have survived the passage, though, and either landed on the surface or floated below the clouds.

Jupiter is the next-brightest planet. It’s hundreds of millions of miles farther out in the solar system. But it’s also the biggest planet. And it, too, is covered by brilliant clouds. In Jupiter’s case, though, the clouds are made mainly of water and ammonia. Only one probe has dropped into the clouds. But there’s no solid surface to land on, so the probe was destroyed by high temperatures and pressures as it descended.

Venus and Jupiter are moving closer together, and will make their closest approach to each other in less than a week — a spectacular encounter between cloudy planets.

We’ll have more about this beautiful morning line-up tomorrow.
 

Script by Damond Benningfield

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Living on Mars wouldn’t be easy. The air is thin and cold. Dust storms can blanket the entire planet. And there’s no magnetic field to block harmful radiation from space.

So some space enthusiasts have suggested that we “terraform” the Red Planet — make it more like Earth. One way to do so would be to create a magnetic field. It would prevent storms on the Sun from eroding the atmosphere. And it would deflect charged particles from the Sun and from outside the solar system.    

Earth’s magnetic field is generated deep inside our planet. Different layers rotate at different rates. That sets up an electric dynamo, which generates the magnetic field.

But Mars’s layers all rotate at the same rate, so the planet hasn’t generated a magnetic field since it was young. But a team from the U.K. and the U.S. found a possible way to make one.

The plan would blast grains of material off one of the small Martian moons. The grains would form a ring around Mars. Solar energy would give the particles an electric charge. Space stations in the same orbit could beam additional energy into the ring to create a magnetic field, and to keep the ring in place.

The team noted that its idea is just a beginning — one possible step toward making Mars more comfortable.

Look for Mars at dawn tomorrow. It looks like a moderately bright star to the left of the Moon. The brighter planets Venus and Jupiter are to their lower left. More about that tomorrow.
 

Script by Damond Benningfield

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Half of the solar system seems to be congregating in the dawn sky right now. The planets Jupiter, Venus, Mars, and Saturn line up in the east and southeast at first light. And over the next few days, the Moon will swing past them.

The planets form such a nice alignment because they all orbit the Sun in roughly the same plane. That plane defines the Sun’s path across the sky, known as the ecliptic. Right now, the four planets are all just slightly south of the ecliptic — by no more than one and a half degrees, which is about the width of your finger held at arm’s length.

The Moon strays a little farther from the ecliptic. That’s because its orbit around Earth is tilted a bit. So over the weeks and months, it swings several degrees to either side of the ecliptic.

At first light for the next week or so, the array will be anchored by Jupiter, the largest planet in the solar system, quite low in the east. Venus, the brilliant “morning star,” will stand close to its upper right. Mars will be well to their upper right, with Saturn about the same distance along the same line. Tomorrow, the Moon will be to the lower right of Saturn.

The configuration will change day by day, though. The Moon will slide past the planets, while Jupiter and Venus inch closer together. They’ll be at their closest on April 30th and May 1st, when they’ll appear to almost touch each other.

More about this beautiful line-up tomorrow.
 

Script by Damond Benningfield

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In January 1848, a worker at Sutter’s Mill, in northern California, discovered gold. That started the California Gold Rush, which attracted hundreds of thousands of people.

A smaller rush was triggered at Sutter’s Mill 10 years ago today. An asteroid exploded above northern California, raining meteorites across the region. Scientists, collectors, and others rushed in to pick up the pieces.

It all began shortly before 8 a.m. A brilliant fireball streaked across the sky, then exploded. Residents across the area saw the fireworks. They also heard booms and rumbles echoing through the foothills of the Sierra Nevada.

Instruments designed to listen for nuclear-bomb tests recorded the explosion. Witnesses shot photos and videos. And weather radar tracked the falling debris. That helped scientists zero in on where meteorites fell.

Researchers determined that the original rock was roughly the size of a minivan, but weighed as much as a Boeing 737. It hit the atmosphere at about 65,000 miles per hour, then blew up at an altitude of 30 miles.

Scientists found the first fragments just a couple of days later. In all, they gathered a couple of pounds of material. Analysis showed that the original asteroid was older than Earth itself. It split away from a larger body tens of thousands of years ago. And it contained many of the chemical building blocks of life — scientific “gold” from Sutter’s Mill.
 

Script by Damond Benningfield

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A “skinny” meteor shower should be at its best tonight. The Lyrid shower turns up every year at this time, and has for at least 2700 years. But the number of meteors is pretty low — about 10 to 20 per hour. In part, that’s because the object that supplies the Lyrids is a long way away.

Lyrid meteors are bits of debris from Comet C/1861 G1 Thatcher. When the comet comes near the Sun, some of its ice vaporizes. That releases bits of rock and dirt into space. Over time, they spread out along the comet’s orbit. Earth flies through that trail of comet dust every April. Some of the particles ram into the atmosphere and vaporize, forming meteors.

A meteor shower is most intense around the time its parent body is closest to the Sun, when it releases fresh debris into space. For Comet Thatcher, that last happened in 1861 — the year it was discovered. Today, the comet is about 10 billion miles from the Sun and moving outward. It’ll be farthest in a few decades. Then it’ll turn around and head sunward, with its closest approach around the year 2276 — when skywatchers may see some great displays of Lyrid meteors.

For now, check out the shower beginning in late evening, as the meteor stream begins to rotate into view. The window is short because the Moon will rise about 2 or 2:30. Its glare will overpower all but the brightest meteors — the offspring of a far-away comet.
 

Script by Damond Benningfield

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NASA plans to send astronauts to the Moon later in this decade. They’ll scoop up rocks and dirt, set up experiments, and begin setting up a base camp. And despite the hard work, they’ll probably have a good time doing it.

But it’ll be hard to have as much fun — or be as enthusiastic — as Apollo 16 astronaut Charles Duke. He and John Young landed on the Moon 50 years ago today.

Duke was making his first trip into space. And he seemed to enjoy every second: bouncing across the surface in a Moon buggy ...

DUKE: ...and we’re — ooik — There it is! There’s Flag! We’re here! You did it! YOUNG: Charlie, you’re hitting my arm. DUKE: Excuse me. YOUNG: You want to wind up in that big crater?

... gathering samples ...

DUKE: Here he comes, folks. He’s got the hammer out. I knew he couldn’t resist. (chuckle) ... Okay, how’s the old heartbeat? MISSION CONTROL: You’re up to about a hundred and forty.

... drilling a hole in the surface ...

DUKE: Okay, are you guys ready? Here we go! Man, that beauty is going right in! MISSION CONTROL: Outstanding!

... or returning to their lander at the end of a long moonwalk ...

DUKE: Hot dog! You did it! ... Home again, home again, jiggety jig! ... Man, Tony, you don’t know how much fun this has been.

During three days on the surface, Young and Duke collected more than 200 pounds of samples, and set up several experiments. They and crewmate Ken Mattingly returned to Earth on April 27th, 1972, after a busy — and apparently fun — trip to the Moon.
 

Script by Damond Benningfield

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Six Apollo missions put astronauts on the Moon. Each flight carried three men. Two of them landed, while the third stayed aboard the command module in lunar orbit. On the surface, astronauts gathered rocks, took pictures, and set up experiments. But the guys they left behind could be just as busy.

Consider Ken Mattingly, the command module pilot for Apollo 16, which arrived at the Moon 50 years ago today. Mattingly stayed in orbit, about 70 miles up, while crewmates John Young and Charles Duke spent three days on the surface.

Mattingly operated a suite of scientific instruments. The gear included cameras, which mapped about six percent of the Moon in high resolution. It also included instruments that mapped the mineral and chemical composition of the ground below, probed for magnetic fields, and looked for traces of an atmosphere. Mattingly also used binoculars to help make his own observations of the Moon.

After Young and Duke rejoined him, they dropped a small satellite into lunar orbit. It was designed to study the solar wind, plus the Moon’s magnetic and gravitational fields. It operated for several weeks before it crashed into the Moon.

During the trip home, Mattingly took a spacewalk — about 200,000 miles from Earth. He plucked film from the cameras, and took out a package containing microscopic life to see how the organisms reacted to space — final chores for a “solo” lunar explorer.

More about Apollo 16 tomorrow.
 

Script by Damond Benningfield

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When the first Apollo astronauts landed on the Moon, it was all about politics. The goal was to get them to the Moon and back by the end of the 1960s, winning a race against the Soviet Union.

But by the time the fifth landing mission headed for the Moon 50 years ago this month, it was all about the science.

LAUNCH CONTROL: Five, four ... The engines now building up to 7.7 million pounds of thrust ... We have a launch commit, and we have a liftoff! The swing arms moving back. We’ve cleared the tower. [11]

Apollo 16 was targeted for a region known as Descartes, in the Moon’s rugged highlands. Earlier missions had landed on the smoother plains. It was thought that Descartes might have been created by volcanoes, and not by asteroid impacts.

Astronauts John Young and Charles Duke landed on April 20th, 1972. They spent three days on the Moon. They made three moonwalks, and drove their lunar rover almost 17 miles. They picked up more than 200 pounds of rocks and dirt. And they set up instruments that operated long after the astronauts returned to Earth.

The samples showed that their landing zone wasn’t built by volcanoes. Instead, the mission demonstrated that volcanic mountains are few and far between — important science from the penultimate mission to the Moon. More about Apollo 16 tomorrow.

Look for the Moon climbing into good view by midnight tonight. It’s trailed by the star Antares, the bright heart of the scorpion.
 

Script by Damond Benningfield

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Four of the five planets that are visible to the unaided eye line up in the early morning sky right now. Only one bucks that trend: Mercury, the Sun’s closest and smallest planet. It’s quite low in the west-northwest as evening twilight begins to fade. It’s bright, though, so if you have a clear horizon, you should be able to spot it.

Mercury will climb higher into the sky over the next couple of weeks. It’ll stand highest on the evenings of the 28th and 29th, providing a little more time to look for it. On the other hand, the planet will get fainter over that period as well. On the 29th, it’ll be about a third as bright as it is tonight.

Several factors are responsible for the changes.

First, Mercury is moving from behind the Sun. It’ll stand farthest from the Sun in our sky late in the month. So each evening, it climbs a little higher into the sky.

Second, the planet is moving closer to Earth — it’ll be about 27 million miles closer on the 29th than it is today. That tends to make it look a little brighter.

But the third factor works the other way. Mercury’s phase is changing, just as the phases of the Moon change. Tonight, the Sun lights up about three quarters of the hemisphere that faces our way. By the 29th, though, it’ll light up only about a third. So while Mercury will be a lot closer to us, it’ll look fainter.

Still, it’s well worth looking for — the only planet in the evening sky.
 

Script by Damond Benningfield

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