StarDate Billy Henry

Jupiter is missing. The solar system’s biggest and heaviest planet is nowhere to be seen. And it won’t return to view for a few weeks.



Jupiter is passing behind the Sun as seen from Earth, so it’s hidden in the Sun’s brilliant glare. It’ll be closest to the Sun on Saturday afternoon. That point is known as conjunction, and it happens every 12 and a half months.



Jupiter is known as a “superior” planet. That means its orbit is outside Earth’s orbit around the Sun. So Jupiter sometimes lines up directly opposite the Sun in our sky, shining brightly all night long. About half a year later, though, it passes behind the Sun and out of sight.



The planet doesn’t necessarily pass directly behind the Sun. This time, for example, it slides about half a degree from the Sun — less than the width of your finger held at arm’s length. Even so, it’s so close to the Sun that astronomers can’t point their telescopes toward it. And radio “static” from the Sun means that flight controllers lose contact with spacecraft at Jupiter for a while. The craft operate on their own, and save their observations to beam to Earth when the Sun is out of the way.



For casual skywatchers, Jupiter should return to view in a month or so. It’ll be quite low in the eastern sky during the dawn twilight. It’ll be in better view as we move into summer — climbing farther from the Sun, and shining like a brilliant beacon in the early morning sky.



Script by Damond Benningfield

The Moon and the heart of the lion stand close together this evening. The lion’s heart is the star Regulus, to the lower right of the Moon at nightfall.



We see Regulus and the Moon for different reasons. Regulus is a star — a brilliant ball of hot gas. It generates its own light — so much light that it’s visible across almost 80 light-years. That means we see Regulus as it looked almost 80 years ago. So if anything big were to happen to the star tonight, Earth wouldn’t know it until early in the 22nd century.



The Moon doesn’t produce any light of its own. Instead, it reflects sunlight. The Moon looks big and bright only because it’s far closer to us than any other celestial object — an average of about a quarter of a million miles. That’s a bit more than one light-second, so we see the Moon as it looked a bit more than one second earlier.



Tonight, the Sun lights up a little more than half of the lunar hemisphere that faces our way. Many people think of that phase as a “half” Moon. And based on its appearance alone, that’s perfectly correct.



But a “half” Moon is also known as a quarter Moon. And at the current angle, it’s the first quarter Moon. That may sound confusing, but there’s a simple explanation: At first quarter, the Moon is one-fourth of the way through its month-long cycle of phases. It’s half of the way through the cycle when it’s full. And the cycle starts over at new Moon — when it’s not visible at all.



Script by Damond Benningfield

A binary star system about 30 million light-years away is an impostor. When astronomers first saw it, they thought it was a supernova — the titanic explosion of a massive star. They even called it one: Supernova 2000ch. But the system is still there.



The system is in the spiral galaxy NGC 3432, in a clump of young, bright, heavy stars.



By the end of last year, 2000ch had produced 23 outbursts. They’ve been about six and a half months apart. Based on that interval, the way the system brightens and fades, and other details, astronomers have developed a model of what’s going on.



The system’s main star is dozens of times the mass of the Sun, and a million times brighter. It’s also unstable — it puffs in and out.



A smaller companion star follows a lopsided orbit. During its close approaches, it stirs up the brighter star, triggering an outburst. And if the main star is in its “puffier” phase, then the outburst is especially bright.



The system may be building up to a much bigger outburst in the fairly near future. And after that, the massive star could explode as a supernova — no longer an “impostor,” but the real thing.



NGC 3432 is in Leo Minor, the little lion. It’s too faint to see without a telescope. But it’s high above the Moon as darkness falls tonight. The bright star Regulus — the heart of the big lion — is to the left of the Moon. More about that meeting tomorrow.



Script by Damond Benningfield

Beta Pictoris is one of the more famous of all star systems. It’s also one of the most complex. It includes a young star, at least two giant planets, lots of gas and dust, and a “cat’s tail” that might be the result of a giant impact.



The star is almost 65 light-years away. It’s about twice as big and heavy as the Sun, and almost 10 times as bright.



In 1983, an infrared space telescope discovered a disk of gas and dust around Beta Pic. It spans hundreds of billions of miles, and contains several wide belts. The belts may consist of debris left over from the collisions of comets and asteroids.



Gaps between the belts contain two known planets. Both of them are more than 10 times the mass of Jupiter, the giant of our own solar system. One of them orbits the star once every three and a third years; the other, once every 24 years.



A smaller second disk also encircles Beta Pic. Last year, Webb Space Telescope discovered a “cat’s tail” of debris curling away from it. It might have formed about a century ago, when a collision between giant chunks of rock and ice shattered the bodies, splashing debris up and away from the disk.



Beta Pictoris is still an infant — it’s only about 25 million years old. So the building blocks around it could still be coming together to make more planets, while others could be destroyed in more big collisions — adding to the complexity of this well-known star system.



Script by Damond Benningfield

The Moon passes especially close to the star Pollux tonight — the brighter “twin” of Gemini. The star stands just to the right of the Moon at nightfall. The other twin, Castor, is farther along the same line.



The Moon always passes closer to Pollux than to Castor. That’s because of the relationships of the three bodies to the ecliptic — the Sun’s path across the sky.



The Moon’s orbit is tilted a bit with respect to the ecliptic. Over the course of a month, it meanders to either side of the ecliptic. And over a period of almost two decades, its maximum distance from the ecliptic varies as well. At most, the Moon can appear 6.6 degrees from the ecliptic — the width of three fingers held at arm’s length. So the Moon can pass close to, or even cover up, any star or planet within that distance from the ecliptic.



Pollux and Castor are outside that zone. Pollux is 6.7 degrees from the ecliptic, while Castor is about 10 degrees away. So the Moon can sometimes appear to almost touch Pollux, while always keeping a little bigger gap with Castor.



Over millennia, the ecliptic shifts with respect to the background of stars. So for thousands of years, the Moon could sometimes pass in front of Pollux, hiding it from view. That last happened about 2100 years ago. Pollux will move back into the Moon’s range in about 10,000 years — setting up some especially close encounters.



Script by Damond Benningfield

It’s hard to think of the White Sands region of New Mexico as confining. It covers thousands of square miles, and few people live there. In the late 1940s, though, the U.S. military was feeling hemmed in. It was launching rockets from White Sands. They could go high, but they couldn’t go very far without flying over towns or cities — a possible danger to residents.



So Congress passed a bill establishing the Joint Long-Range Proving Ground at Cape Canaveral, on the Atlantic coast of Florida. President Harry Truman signed it into law 75 years ago today.



“The Cape,” as it’s been known for most of those years, offered many advantages. The region had a small population, the climate wasn’t too extreme, and there were thousands and thousands of miles of ocean to plop rockets into. Launches to orbit have benefited from its southern location — rockets get a “boost” from Earth’s rotation.



It took a year to clear away some of the scrub and build the early launch pads. The U.S. Army launched its first rocket there in July of 1950 — an American-built version of the German V-2 terror weapon.



Since then, thousands of rockets have taken flight from the Cape and the facilities on nearby Merritt Island. They’ve sent satellites into orbit, astronauts to the Moon, and probes to all the planets of the solar system — and beyond. And today, the facilities are busier than ever — at the first American spaceport.



Script by Damond Benningfield