StarDate

Few of us have to hunt wild game to survive the long, cold winter these days. But that hasn’t always been the case. Native tribes and European settlers alike had to stock up as the weather grew cooler. And they relied on an autumn full Moon for help: the Hunter’s Moon.

And that Moon is coming up tonight. It’s the full Moon after the Harvest Moon, which appeared in September.

Like the Harvest Moon, the Hunter’s Moon helped people prepare for winter. Its light made it easier to see deer and other animals. And at high northern latitudes, the Moon rises only about a half-hour later each night around full Moon – a much smaller gap than average. So the big, bright Moon was in view by the time evening twilight faded – allowing hunters to stay in the fields long into the night.

Despite what you might think, the Harvest and Hunter’s Moons aren’t any bigger and brighter than any other full Moons. The Moon’s orbit and its cycle of phases aren’t synchronized. So some years the Hunter’s Moon is closer than average. But in other years, it’s farther than average. This year we’re in luck, because it’s on the closer side. At the moment of full Moon, it’ll be about 230,000 miles away – a few thousand miles closer than average.

That helps make this year’s Hunter’s Moon an especially beautiful sight, lighting the autumn fields for hunters – and everyone else, too.

Tomorrow: stretching the year.

Script by Damond Benningfield

Twenty-five years ago, NASA needed a hit. Its previous two missions to Mars had failed – both of them as they were arriving at the Red Planet. So it prepared the next mission with extra care, and sent it on its way on April 7th, 2001.

The craft was named 2001 Mars Odyssey – a tribute to Arthur C. Clarke, the author of “2001: A Space Odyssey.” And like most of Clarke’s books, Mars Odyssey was a big hit. It entered orbit around Mars on October 23rd – 25 years ago this week. It’s the longest-operating spacecraft at any body in the solar system other than Earth.

Among its many accomplishments, Odyssey has mapped the chemical and mineral composition of the entire Martian surface. It also discovered evidence of vast amounts of ice just below the surface. And it found places where liquid water once pooled on the surface. Those observations helped scientists pick interesting locations for landers and rovers. And it found the first caves ever seen on Mars – possible places for future missions to look for microscopic life.

Odyssey also has served as a relay station for Mars landers and rovers. And it recorded radiation levels at the planet – critical information for planning human missions.

As of late summer, the craft was still going. And barring any unexpected problems, it could add several more years to its record-breaking odyssey at the Red Planet.

Script by Damond Benningfield

If you ignore the dark orange sky and the extreme cold, Saturn’s moon Titan might remind you of Earth. River channels empty into lakes and seas. Giant fields of dunes ripple across the surface. And clouds float through the sky, producing occasional rains.

And if everything goes to plan, we should get some amazing views of that landscape in the next decade. A nuclear-powered “octocopter” will fly across the surface, covering several miles with each trip. It’ll monitor the weather and analyze the soil. Most important, it’ll search for elements of life – and evidence of life itself.

Dragonfly is one of the most ambitious missions yet conceived. It’s scheduled for launch in 2028, and arrival at Titan six years later.

Titan is about half-again the size of Earth’s moon. It has a cold, dense atmosphere that’s topped by “smog.” The atmosphere, surface, and lakes appear to contain lots of organic compounds – the building blocks of life. Except for the extreme cold, it may be a lot like Earth was about three-and-a-half billion years ago – at the dawn of life on our planet. So Dragonfly will help scientists determine if Titan is habitable – another home for life.

Saturn is near our moon tonight. It’s close to the lower left of the Moon at nightfall, and even closer as they set, before dawn. It looks like a bright star. But you need a telescope to spot Titan – the target for a dragonfly.



Script by Damond Benningfield

The night sky is disappearing. Growing cities and towns pump more artificial light into the sky all the time. That creates a glowing dome that blots out the view of the Milky Way, meteors, and other beautiful but faint sights.

Light pollution does more than make it impossible to appreciate the beauty of the night sky. It can interfere with the migrations of many animals, and it can harm human health. And it wastes energy by shining light into the sky instead of onto the ground, where it’s needed.

In recent decades, though, some places have tried to limit the light pollution. They’ve passed laws that restrict outdoor lighting, keeping the sky as dark as possible. An international organization certifies the most successful ones. And number one on the list was Flagstaff, Arizona. It was declared the first International Dark-Sky City 25 years ago this week.

Flagstaff began protecting the night in 1958. Lowell Observatory was adding a big new telescope, and it needed dark skies to get the best results. So the city placed restrictions on outdoor lighting. As the city grew over the following years, it beefed up those regulations, winning certification in 2001.

Today, there are more than 60 dark-sky communities, plus dozens of dark-sky parks, reserves, and other sites. That includes a wide swath of West Texas, which is home to McDonald Observatory. These locations help keep the night sky from disappearing.



Script by Damond Benningfield

William Lassell made a fortune selling beer to factory workers in Liverpool. He used that money to set up his own astronomical observatory, called Starfield, outside Liverpool. And he equipped it with telescopes he built himself – some of the best in the world.

Using one of those instruments, Lassell made a major discovery 175 years ago this week. Make that two discoveries: two large moons of the planet Uranus. They were named Ariel and Umbriel, after characters from the works of William Shakespeare and Alexander Pope.

The moons are almost exactly the same size – about 720 miles in diameter. And they have a similar makeup – mixtures of rock and frozen water and methane.

But they look different. Umbriel is dark, and it’s covered by many large impact craters. That suggests the moon is quiet and still – not much happens there.

Ariel is brighter, and it’s much more interesting. It’s crossed by giant canyons and cliffs, with few craters. Liquid water may bubble to the surface from an underground ocean. At the surface, it freezes. That may push the surrounding crust, causing it to crack. So Ariel may be an active world orbiting a giant planet.

Uranus is an easy target for binoculars. It’s halfway between Aldebaran – the bright eye of the bull – and the Pleiades star cluster. They climb into good view in late evening. But the view will be better before dawn, after the Moon has dropped from sight.

Script by Damond Benningfield