StarDate

The waning Moon anchors a beautiful lineup in tomorrow’s early-morning sky. At dawn, the star Regulus – the heart of the lion – is close above the Moon. The brilliant planet Jupiter is to the upper right of the Moon, with Mars a little farther along the same line.

Mars and Jupiter are the fourth and fifth planets from the Sun, with Jupiter about three times farther out. The gap between them is more than 300 million miles. But that space is far from empty. Instead, it’s home to the asteroid belt – a wide band of debris.

So far, astronomers have cataloged about one-and-a-half million objects in the belt. The largest is about 600 miles across. The smallest are about the size of a bus. But the suspected population is far larger. There could be more than a million that are at least one kilometer in diameter, and millions upon millions of smaller ones.

Current theories say the belt probably is debris from a planet that never was. Many of the solid chunks of material that came together to form the planets inhabited the region when the solar system was young. Left on their own, they might have come together to make a planet. But Jupiter’s gravity kept that from happening. It kicked many of the pieces out of the solar system. And it stirred up the others, preventing them from coalescing – filling the space between Mars and Jupiter with a bunch of leftovers from the birth of the planets.

Script by Damond Benningfield

There’s a spectacular lineup in the wee hours of the morning the next couple of days: the Moon, the planets Mars and Jupiter, and the star Regulus. The entire lineup climbs into good view by 1:30 or 2, and is high in the sky at first light.

Tomorrow, the Moon will be especially close to Mars. At their closest, they’ll be about one degree apart – the width of a pencil held at arm’s length. The planet looks like a bright star. But it might be tough to see its orange color through the moonlight.

Mars is the fourth planet from the Sun – the next one out beyond Earth. It’s also the Sun’s fourth-smallest planet – a little more than half the diameter of Earth.

Jupiter stands below them as they climb skyward. It’s much brighter than Mars. In fact, it’s brighter than anything else in the night sky other than the Moon and Venus, which is pulling into view as the “morning star.”

Jupiter is the next planet out. And it’s the largest planet in the solar system – about 11 times Earth’s diameter. That’s one reason it looks so bright, even though it’s about three times farther than Mars.

Regulus is about the same distance below Jupiter. It’s the faintest member of the lineup. But it’s one of the brighter true stars in the night sky, so you won’t have any trouble picking it out. It represents the heart of Leo. The Moon will stand especially close to it on Tuesday, and we’ll have more about that tomorrow.

Script by Damond Benningfield

Ghosts and demons roam the Halloween night. Vampires and zombies are there, too. So are black widows and Gorgons, witches and snakes and dragons – enough scary creatures to fill a galaxy of haunted houses. You’ll see some of them wandering the streets in search of treats. And if you look up, they’re all there in the stars.

As night falls, the star Algol is in the northeast, in Perseus the hero. Its name means “the demon star.” It represents Medusa, a monster who turned anyone who looked at her to stone. Her sisters – the other Gorgons – are represented by some fainter stars around Algol.

The constellation Cetus is low in the east and southeast. It represents a sea monster that was defeated by Perseus – using the head of Medusa.

The Witch Head Nebula climbs into view in late evening. It’s a cloud of gas and dust that’s being both illuminated and sculpted by Rigel, the brightest star of Orion. Through a telescope, it really does look like the profile of a witch.

Many “ghosts” float through the sky as well. They’re star clusters or the last gasps of dying stars – named for their ghostly appearance.

The vampires and zombies and black widows are all “dead” stars that are sucking the life from their companion stars. They’re all invisible – none of them is bright enough to see with the eye alone. But they’re sprinkled through the galaxy, haunting the skies of Halloween night – and every other night as well.

Script by Damond Benningfield

Several of the brightest stars in the night sky are really systems of at least two stars. But only one of those systems is known to contain six stars: Castor, the fainter “twin” of Gemini. It’s to the left of the gibbous Moon as they climb into good view late tonight, and to the upper left of Gemini’s brighter twin, Pollux.

Seen across 50 light-years of space, the light from all six stars blurs together to form a single point. But binoculars reveal two points, known as Castor A and Castor B. Castor A is the brighter of the two. Because of our viewing angle, the distance between the two pairs is getting bigger, so it’s easier to see them as separate points of light.

It turns out that A and B are both binaries – each of them consists of two stars. The stars in each pair are quite close together, so there’s no way to see them individually. Instead, their dual nature is revealed only by sensitive instruments.

One star in each pair is bigger, hotter, and brighter than the Sun. The other star in each pair is much smaller, cooler, and fainter than the Sun – a cosmic ember known as a red dwarf.

Castor’s third pair is Castor C. It’s a long way away from the other two. And both of its stars are red dwarfs, so the pair is quite faint – you need a telescope to pick it out. Even so, it helps make Castor the busiest bright star system in the night sky – three pairs of “twins” for the twins’ constellation.

Script by Damond Benningfield

The tiny moons of Mars are hard to explain. Scientists aren’t sure how they formed and how they wound up in their current orbits. But a Japanese mission that launched this month could settle the conundrum.

The mission is MMX – Mars Moons Exploration. It will scan both Phobos and Deimos – chunks of rock the size of a small city. And it will land on Phobos, gathering samples for return to Earth.

Both moons are dark, like a class of asteroids. In fact, astronomers long suspected they were captured asteroids. In this scenario, rocky “leftovers” from the birth of the planets flew close to Mars. The planet was surrounded by a cloud of gas and dust. As Phobos and Deimos passed through it, the cloud acted as a brake, slowing them enough for Mars to grab them.

But it’s not easy for a planet to capture an asteroid. And the orbits of the moons aren’t like those of the captured asteroids of the giant outer planets.

So scientists came up with another model: a giant impact. A massive space rock could have slammed into Mars, blasting out material that formed a ring around the equator. The debris coalesced to form several small moons. Phobos and Deimos are the only survivors.

In yet another scenario, Mars captured a single large asteroid. It was sheared apart by Martian gravity, creating a ring that gave birth to Phobos and Deimos.
MMX will arrive at Mars next year – a big step toward solving the mystery of the Martian moons.



Script by Damond Benningfield