StarDate

Mars, Mercury, and the Moon have more in common than just the letter M. All three are small, rocky worlds. They all have large deposits of ice at their poles. And for the next couple of days, they clump together in the dawn sky.

The Moon is the smallest member of the trio — about 2200 miles in diameter. Mars is twice that size, with Mercury half way between the two.

All three are balls of rock and metal. Mercury has a big, heavy core of iron and nickel. That makes it the second-densest planet in the solar system, behind Earth. The Moon has a metallic core as well. It’s not nearly as big in proportion to the Moon’s overall size, though, so the Moon is much less dense. The Martian core isn’t well understood. But a lander is probing the planet’s interior by listening for “marsquakes.” That should give us a better idea of how Mars is put together.

Orbiting spacecraft and ground-based radio telescopes have found evidence of big deposits of ice at the poles of Mercury and the Moon. They’re hidden inside craters that never see the light of day.

You don’t have to look hard to find the ice on Mars, though. The planet has giant ice caps at both poles — some of the most prominent features on the Red Planet.

Look for the Moon, Mars, and Mercury before and during dawn’s early light the next couple of days. Mars will stand close to the right of the Moon tomorrow, with Mercury farther below the Moon. The Moon will perch below Mercury on Monday morning.

Script by Damond Benningfield

A star system with an explosive future stands to the lower right of the Moon early tomorrow. One of the system’s two known stars is massive enough to end its life as a supernova.

Spica is the leading light of the constellation Virgo. It’s only about 250 light-years away. That makes it the closest supernova candidate in its category.

That category is known as a “Type 2” supernova. Such a blast occurs when a massive star reaches the end of its life. Its core can no longer produce nuclear reactions. Without the energy from those reactions to push against the pull of gravity, the core collapses. The surrounding layers of gas fall inward, then rebound — blasting themselves to bits. For a while, the explosion can outshine billions of “normal” stars.

And that’s the likely fate of the heavier of Spica’s two stars. It’s more than 11 times the mass of the Sun — well above the limit for becoming a supernova. And it’s already gone past the end of its “normal” lifetime, so the clock is ticking toward its demise.

The future is a bit hard to see, though, because of the second star in the system. The two stars are extremely close together. Over the next few million years, the heavier star will get much bigger. Eventually, it will engulf its companion. Just how that’ll affect the evolution of the two stars is uncertain. But it’s unlikely to prevent the fireworks from Spica’s massive star.

We’ll talk about the Moon and some other dawn companions tomorrow.

Script by Damond Benningfield

A star can be both young and old at the same time. It can be young compared to other stars, yet old in terms of its own life cycle.

An example is Deneb Kaitos — a name that means “the tail of the whale.” The star marks the tail of Cetus, the whale or sea monster. The star is in the southeast at nightfall. It’s to the upper left of the only bright star in that region of the sky, Fomalhaut. Deneb Kaitos is the next-brightest star around, so it’s fairly easy to pick out.

Deneb Kaitos is a little more than a billion years old. That’s pretty young for a star. By comparison, the Sun is four and a half billion years old. And many stars are billions of years older than that.

But Deneb Kaitos has already moved out of the prime of life. That’s because of its mass — almost three times the mass of the Sun. Heavier stars burn through their nuclear fuel much faster than lighter stars, so they live shorter lives.

Deneb Kaitos has converted the original hydrogen in its core to helium. Now, it’s fusing the helium to make heavier elements. It’ll stay in that phase of life for another hundred million years, getting bigger and brighter as it does so.

When that phase is over, the star will cast its outer layers into space. For a while, it’ll surround itself with a colorful bubble of gas and dust. The bubble will quickly fade away, though. That will leave only the star’s hot but dead core — a white dwarf — and the tale of the tail of the whale will come to an end.

Script by Damond Benningfield

The two brightest points of light in the night sky are having a bit of a get-together. They’re quite low in the southwest as the Sun sets, though, so there’s not a lot of time to look for them before they set.

The brighter light is Venus, the second planet from the Sun. It’s just beginning a run as the “evening star,” so it’s climbing a little higher each night. By year’s end, it’ll be in view for a couple of hours.

Venus is just emerging from behind the Sun. So right now, sunlight is illuminating most of the planet’s hemisphere that faces our way — one reason it looks so bright. On the other hand, it’s about as far away as it can get without being hidden behind the Sun. That takes away some of its luster. Put them together, though, and Venus shines brightly.

Venus’s companion is Jupiter, the Sun’s largest planet. It stands a little to the upper left of Venus this evening.

While Venus is moving away from the Sun as seen from Earth, Jupiter is dropping toward it. It’s also near its greatest distance from Earth, which means it’s not at its peak brightness. Even so, it still outranks every other planet and star in the night sky other than Venus.

Look for this brilliant duo beginning shortly after sunset. You’ll need a clear horizon to spot them. But they should be easy to pick out through the fading twilight. And watch over the next few days as they slide past each other, with Venus climbing higher and Jupiter dropping from sight.

Script by Damond Benningfield

PETE CONRAD: There it is! Son-of-a-gun! Right down the middle of the road! ALAN BEAN: Outstanding, Pete. CONRAD: I can’t believe it! Amazing! Fantastic!

Pete Conrad and Alan Bean had reason to be excited. 50 years ago today, the Apollo 12 astronauts were moments away from making the second manned lunar landing. And Conrad had just spotted their target: a small crater holding Surveyor 3, a robotic lander that had touched down more than two years earlier.

Future Apollo missions would be focused more on science, requiring pinpoint landings at interesting sites. So Apollo 12 was testing the ability to hit a precise target. And Conrad, flying the Lunar Module Intrepid, did just that.

BEAN: He’s got it made. Come on in there. 24 feet. Contact light! MISSION CONTROL: Roger, copy contact. BEAN: Good landing, Pete! Outstanding, man! Beautiful!

A few hours later, Conrad stepped on the lunar surface for the first of two moonwalks.

CONRAD: Hey, that’s neat.

The astronauts set up experiments and gathered samples of rock and dirt.

CONRAD: We’re just going to more to the area where we can stop and case the joint. Al, grab a shot of that beaded glass there and we’ll bag it. BEAN: Okay. CONRAD: That’s better than the Hope Diamond.

Then they walked down to the Surveyor, just 500 feet away.

BEAN: Beautiful. Beautiful sight.

Conrad and Bean clipped off some parts for engineers on Earth to study. Hours later, they blasted off to rejoin crewmate Richard Gordon for the trip home — ending a precise mission to the Moon.

Script by Damond Benningfield

Pete Conrad and Alan Bean had just completed their first moonwalk 50 years ago this week. The Apollo 12 astronauts were the second crew to land on the Moon. And during four hours on the surface, they’d set up scientific instruments and gathered rocks and dirt.

Most of the samples were stored in bags. But the astronauts tracked a lot of dust into their Lunar Module, Intrepid, as Conrad told Mission Control:

CONRAD: Man, oh man, is it filthy in here. We must have 20 pounds of dust, dirt, and all kinds of junk. Al and I look like a couple of bituminous coal miners right at the moment. But we’re happy.

The engineers who are planning future lunar missions aren’t happy about the mess. Many of the Moon’s dust grains are jagged. That makes them cling to just about everything. They could easily damage important systems. And they could stick in astronauts’ lungs, perhaps causing health problems.

So future moonwalkers may need help keeping the dust outside. They might wear spacesuits that could dock to the outside of their landers, for example. The astronauts would crawl in and out through the back of the suits, without having to bring them indoors.

Whatever the solution, lunar explorers will need to keep clean — and not look like coal miners.

More about Apollo 12 tomorrow.

In the meantime, look for the Moon high in the sky at first light tomorrow. Regulus, the star that marks the heart of the lion, will stand to the lower left of the Moon.

Script by Damond Benningfield

Our home galaxy, the Milky Way, belongs to the Local Group — a small cluster of dozens of galaxies. It contains two heavyweights — the Milky Way and the Andromeda Galaxy. It also has a few middleweights, and a whole bunch of bantamweights — tiny puffs of stars and gas.

But there’s only one that might be called a light heavyweight: M33. It’s in the tiny constellation Triangulum, so it’s also known as the Triangulum Galaxy.

Like the Milky Way and Andromeda, M33 is a spiral galaxy. It consists of a flat disk of stars. Its younger, hotter stars outline beautiful spiral arms.

M33 isn’t nearly as monstrous as the Local Group’s heavyweights, though. It’s about half the diameter of the Milky Way. And it probably has only about a tenth as many stars.

It does outperform both of the bigger galaxies in one category, though: star production. Given its size, it’s churning out far more new stars.

Many of them are being born in a single stellar nursery, NGC 604. It’s one of the most impressive star-forming regions in the entire Local Group. It’s given birth to thousands of stars, including a couple of hundred that are dozens of times the mass of the Sun.

Under especially clear, dark skies, M33 is just visible to the unaided eye. In fact, it’s one of the most-distant objects visible to the eye alone — close to three million light-years away. As night falls, it’s above Triangulum’s triangle of stars — a galaxy that’s in a class of its own.

Script by Damond Benningfield

Most of the night sky is populated with heroes, monsters, and even the tools of science. In a few cases, though, imagination failed the folks who named the constellations.

An example is Triangulum. The skinny triangle is wedged between four bigger constellations with big stories, including Andromeda the princess and Perseus the hero. The triangle, though, has no real story at all.

It is one of the older constellations, though. It dates back to ancient Greece. The Greeks named the star pattern for its resemblance to the capital letter “delta.” At various times it’s been compared to the delta of the Nile River, and to the island of Sicily.

None of Triangulum’s three stars is all that prominent. The brightest of them is Beta Trianguli. It’s so faint that, from a light-polluted city, you might not see it at all.

Beta Trianguli is about 127 light-years away. It consists of two stars. They’re so close together, though, that even the biggest telescopes can’t see them individually — their light blurs together into a single point.

The system’s main star is about three and a half times as massive as the Sun. And it’s nearing the end of its life, so it’s puffing up. Millions of years from now, it’ll shine much brighter — making the triangle stand out.

For now, if you have a dark sky, look for Triangulum well up in the east at nightfall. The wedge aims to the right, with Beta Trianguli at the top left point.

We’ll have more about Triangulum tomorrow.

Script by Damond Benningfield

A minor dust storm will sweep into Earth’s upper atmosphere the next few nights. It’ll produce a smattering of meteors. But a much brighter light source — the Moon — will overpower the show. Only the brightest of the “shooting stars” will shine through the moonglow.

The Leonid shower takes place every November, as Earth crosses the path of Comet Tempel-Tuttle. The comet sheds small bits of dirt and rock as it orbits the Sun. These grains of material spread out along the orbit, forming a thin cloud.

As Earth plows through the cloud, bits of the debris plunge into the atmosphere at high speeds. They quickly vaporize — forming the glowing streaks of light known as meteors.

The Leonids are expected to be at their best before dawn on Monday. As many as a score of meteors might punctuate the sky every hour. With the Moon around, though, you probably won’t see many of them.

But you don’t have to wait for a shower to see meteors. They streak across the sky every night of the year. A few stragglers from the Leonids, for example, are visible for a week or two before and after the shower’s peak.

Other meteors aren’t related to any shower at all. Tiny bits of debris from asteroids and comets are scattered throughout the solar system. Earth sweeps up some of these grains every night.

The main thing you need to enjoy them is a dark sky. Find a moonless night, get away from city lights, then look up and enjoy the fireworks — all year long.

Script by Damond Benningfield

Astronauts Pete Conrad, Alan Bean, and Richard Gordon were ready to head to the Moon. Rain and heavy clouds hung over their launch pad, but engineers decided they wouldn’t be a problem. So Apollo 12 headed skyward 50 years ago today.

LAUNCH CONTROL: 3, 2, 1, zero, all engines running! Commit, lift off! We have a lift off!

Seconds later, though, something went wrong.

APOLLO 12: What the hell was that? I lost a whole bunch of stuff.

Mission Control lost data, and the systems in the spacecraft went haywire.

APOLLO 12: Okay, we just lost the platform gang. I don’t know what happened, we had everything in the world drop out. ...Fuel cell lights, an A/C bus light, a fuel cell disconnect, A/C bus overload 1 and 2, main bus A and B out.

Without guidance and power, the crew might have had to abort. But 26-year-old flight controller John Aaron saved the day by recommending that the crew flip a little-known switch.

MISSION CONTROL: Apollo 12, Houston. Try S-C-E to auxiliary, over.

That reset the power, allowing the flight to continue. A bit later, Pete Conrad deduced what had happened:

CONRAD: We’re okay now. We’ve straightened out our problems here. I don’t know what happened. I’m not sure we didn’t get hit by lightning.

Lightning had indeed zapped the craft. But quick work by Mission Control and the astronauts overcame the problem — allowing Apollo 12 to make the second landing on the Moon. More about that next week.

Script by Damond Benningfield