StarDate

Vega, one of the brightest stars in the night sky, may be orbited by one of the hottest planets. The planet hasn’t been confirmed. But in early observations, it appears to be about 20 times the mass of Earth. And it’s so close to Vega that daytime temperatures soar to 5400 degrees Fahrenheit. That easily puts it on the list of hottest known exoplanets.

Astronomers have discovered hundreds of super-heated planets. The heat can melt the planet’s surface and create fearsome winds and hellish rains.

On HD 189733b, for example, the thermostat is cranked up to 1700 degrees. That appears to create winds between the dayside and the cooler nightside of about 9,000 miles per hour. It may also form clouds that rain beads of molten glass.

And WASP-76b, with peak temperatures of 4,000 degrees, could see rains of molten iron, with winds howling at 50,000 miles per hour.

The hottest planet yet seen is KELT-9b. It’s near the middle of Cygnus, the swan, which is low in the northeast at nightfall, to the lower left of brighter Vega.

KELT-9b is bigger and heavier than Jupiter, the giant of our own solar system. It orbits a Sun-like star at just one-tenth of the distance from the Sun to its closest planet. So KELT-9b may top out at 7800 degrees — hotter than most stars. The planet’s atmosphere may be boiling off into space, forming a “tail” of super-hot gas behind a super-hot planet.
 

Script by Damond Benningfield

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One of the most brilliant stars in the night sky is a dominant presence from late spring through autumn. Vega is the fifth-brightest star in all the night sky. It’s about a third of the way up in the east-northeast at nightfall now, and climbs high overhead later on.

Vega is just 25 light-years away — a close neighbor. That’s one reason it appears so bright. But it really is an impressive star. It’s more than twice as big and heavy as the Sun, and about 40 times brighter.

Vega is encircled by a disk of dust. Such disks can provide the raw materials for planets. Vega is already about 450 million years old, though, which is well beyond the expected planet-birthing years. So the disk isn’t likely to spawn any new planets.

But Vega might already have a planet.

Astronomers looked at a decade of observations of Vega. The observations ruled out many possible types of planets — including one that was hinted at in some earlier work. But they did suggest that a planet about 20 times the mass of Earth orbits Vega every two and a half days.

The discovery isn’t especially solid. But if the planet’s really there, it orbits Vega roughly around its poles, not around the equator, as Earth orbits the Sun. And it’s so close to Vega — a hot, bright star — that it would be one of the hottest planets yet seen: roughly 5400 degrees on its dayside — a broiling planet around a hot star.

More about super-hot planets tomorrow.
 

Script by Damond Benningfield

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We’re sorry if it makes you feel a bit squeamish, but trillions of ghostly particles from beyond Earth zip through your body every second. Known as neutrinos, they’re not harmful, because they almost never interact with other matter. In fact, they can pass through an entire planet or even a star without so much as a wiggle.

That’s good for planets and stars, but not so good for astronomers. They want to study neutrinos because they’re produced in stars, exploding stars, and other powerful objects and events. So they can reveal details about what’s going on inside those objects. If neutrinos aren’t affected by other matter, though, it’s impossible to catch them. And if you can’t catch them, you can’t really study them.

Every once in a while, though, a neutrino does cause a reaction from another bit of matter — a faint flash of light.

And 25 years ago today, scientists announced something new revealed by the flashes: neutrinos have mass. Before that discovery, it was thought that neutrinos had no mass at all.

It was known that neutrinos come in three varieties, called flavors. Using a detector buried far beneath a Japanese mountain, the scientists found that some neutrinos can change flavor. The only way that could happen is if neutrinos have mass.

The mass is tiny. Still, there are so many neutrinos that it adds up — a bit of substance from some ghostly particles.
 

Script by Damond Benningfield

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Visitors to the Grand Canyon will find a bonus beginning on Saturday: the Grand Canyon Star Party. The week-long party will offer tours of the night sky, telescope viewing, and other events on both the north and south rims. And the only cost is the usual park entry fee.

If you can’t make it, though, don’t worry — there are plenty of star parties to go around — from California to Maine, Washington to Florida. COVID-19 wiped out many events in 2020 and beyond. But most of them are back this summer.

Some will be held in national parks, such as Grand Canyon and Bryce Canyon, in Utah, which offer especially dark skies. Others are hosted by private groups, although they, too, seek out parks and other locations far from city lights. The big parties last for days, with many attendees camping on site.

Many other groups, such as museums and observatories, offer shorter events — a night here and there. Some are free, some are not. But most offer nice views of the night sky for novices and veterans alike.

Of course, we’re partial to the star parties at McDonald Observatory. During the summer months, they’re generally offered four nights a week, beginning about the time the sky gets good and dark. Experts provide naked-eye tours of the stars under some of the darkest skies in North America. And several telescopes offer up-close views of galaxies, nebulas, planets, and other astronomical wonders — at parties that celebrate the beauty of the universe. You can find details at mcdonaldobervatory.org.
 

Script by Damond Benningfield

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Giant new telescopes pop up like mushrooms these days — there’s another one every year or two. And even bigger ones are on the way.

But one telescope reigned supreme for almost three decades: the 200-inch at Palomar Observatory in southern California. It was dedicated 75 years ago today. At the ceremony, the president of Caltech, which operated the telescope, announced that it was being named for a pioneering astronomer...

LEE DUBRIDGE: George Ellery Hale, who served as director of the Mount Wilson Observatory from 1904 to 1923, who originated the bold conception of the 200-inch telescope, and whose brilliant leadership made possible its design and construction.

Hale had founded Yerkes Observatory in Wisconsin, then moved to the clearer skies of California, where he founded Mount Wilson and built its 100-inch telescope — the largest in the world until the 200-inch came along. He also established a lab for studying the Sun.

Hale kept pushing for bigger telescopes and better instruments, and got the funding for the 200-inch in the 1930s. Development problems and World War II delayed its completion until 1948 — a decade after Hale died.

Since then, the telescope has made major contributions to every field of astronomy, from the planets of the solar system to distant galaxies and quasars. And although it’s no longer the world’s largest — it’s barely in the top 20 — it’s still busy every clear night, keeping a giant “eye” on the stars.
 

Script by Damond Benningfield

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The Moon will be full tomorrow night. It’s the Flower Moon, Rose Moon, or Strawberry Moon. But it can also be called the Short Moon or Short-Night Moon. It puts in one of the shortest appearances of any full Moon of the year. Only July’s Moon will surpass its brevity — but not by much.

These Moons are so bashful because the full Moon does the opposite of what the Sun is doing in our sky. These are the longest days of the year in the northern hemisphere, so the Sun remains in view for a long time. It also stands highest in the sky for the year.

So the full Moon does just the opposite: It stays fairly low, and with the shortest nights of the year upon us, it’s in view for only a few hours.

The difference is more pronounced as you go farther north. Miami, for example, sees about 13 and a half hours of sunlight the next few days, but as little as 10 and half hours of moonlight. From Dallas, it’s more than 14 hours of the Sun, but only 10 hours of the Moon. And from Seattle, it’s 16 hours versus just eight.

The Short Moon is the full Moon closest to the summer solstice, which is June 21st — 18 days after tomorrow night’s full Moon. July’s full Moon comes on the 3rd — 11 days after the solstice. It’ll be in view for a few minutes less than June’s Moon. So, technically, it earns the Short Moon tag. But both full Moons will be so scarce that they might as well share this year’s honors: the Short-Night Moon.
 

Script by Damond Benningfield

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Mars and Venus will pass near a star cluster with many aliases this month. It’s probably best known as the Beehive. But it’s also known as Praesepe — Latin for “crib” or “manger” — as well as Messier 44 and NGC 2632. Astronomers have many other names for it, most of which are long catalog numbers.

The cluster is in Cancer, the crab. From a distance of at least 600 light-years, it looks like a hazy smudge of light. Binoculars reveal there’s more to it — a swarm of stars that looks like bees buzzing around their hive.

Astronomers have identified about a thousand members of the cluster. A few are bigger and brighter than the Sun, and congregate in the cluster’s middle.

But most of the bees are much fainter and smaller than the Sun. They spread up to a few dozen light-years from the core. Those stars won’t hang around forever, though. They’re being tugged by the gravity of the galaxy’s other stars and gas clouds. Eventually, they’ll be stripped away and head off on their own.

Mars will pass directly across the cluster over the next couple of nights. They’re a third of the way up the western sky at nightfall, to the upper left of Venus, the “evening star.” Mars looks like a fairly bright orange star.

Mars will move away from the cluster after tomorrow night, with Venus closing in on it night by night. Venus will be closest on the 12th — an encounter with a star cluster with lots of aliases.
 

Script by Damond Benningfield

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The Sombrero Galaxy has taught us a lot. It provided important details about the birth, scale, and evolution of the universe. And it’s a good laboratory for studying the birth of stars and the feeding habits of giant black holes.

The Sombrero is about 30 million light-years away. It forms a disk that we see almost edge-on. It has a bright “bulge” of stars in the middle, and a lane of dark dust around its rim. That makes it look like a sombrero.

In 1912, V.M. Slipher discovered that the galaxy is moving away from us at about 25 million miles per hour. At the time, astronomers were debating whether the entire universe was contained inside the Milky Way. Slipher’s discovery indicated that the Sombrero was a separate galaxy, far beyond the Milky Way. It also suggested that the universe was expanding.

The galaxy has a central black hole that’s roughly 250 times the mass of the Milky Way’s black hole. It appears to be “feeding” on massive amounts of gas, perhaps funneled in from outside the galaxy.

Stars are being born in the galaxy’s ring of dust. Studying that process can tell astronomers more about how stars are born — all from the “brim” of a galactic sombrero.

The Sombrero is in Virgo. The Moon is passing through the constellation tonight, with Virgo’s leading light, Spica, close to its upper right. The Sombrero is about the same distance to the lower right of Spica, and is an easy target for telescopes.
 

Script by Damond Benningfield

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The Moon stands near the middle of the largest member of the zodiac tonight, the constellation Virgo. Spica, the maiden’s brightest star, is close to the Moon as darkness falls, and the Moon will slide a little closer to it during the night. Spica represents an ear of wheat held in the maiden’s hand.

Virgo is the second largest of all the modern constellations. Only Hydra, the water snake, outranks it. But it’s not the size of the constellation that’s made it one of the most important. Instead, it’s the fact that the Sun passes through its borders at the time of the September equinox — the beginning of autumn in the northern hemisphere.

Because of Virgo’s great size, the Sun spends a long time inside its borders — more than seven weeks — from mid-September until the end of October. That’s longer than it stays inside any other constellation.

But the Sun hasn’t always been passing through Virgo at the equinox. Until about the year 730 B.C., it was in the adjoining constellation Libra.

The change is due to precession — a slow “wobble” of Earth’s axis. It takes about 26,000 years to complete one wobble. During that time, the Sun glides through the background of stars. That means the point of the equinox changes as well. It’ll shift over into Leo in about 400 years. And it’ll return to Virgo about 23,000 years after that — returning to the largest constellation of the zodiac.
 

Script by Damond Benningfield

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Mars is moving at a leisurely pace — slower than at any other time during its almost two-year orbit around the Sun. That’s because it’s farthest from the Sun — 13 million miles farther than average. So the planet is coasting at about 50,000 miles per hour — thousands of miles per hour slower than its average speed.

Neither Mars nor any other planet follows a circular path around the Sun. Instead, their orbits are elliptical — they’re stretched out. And the orbit of Mars is more stretched than most. Its distance from the Sun varies by almost 10 percent in either direction.

Those details were worked out four centuries ago, by Johannes Kepler. At the time, astronomers assumed that the planets all followed circular orbits — perfect shapes. But Mars’s motion didn’t fit that idea.

Kepler pored through years of observations, mostly by his boss, Tycho Brahe. He then spent more years analyzing those observations. From that, he developed several laws of planetary motion. The first law says that Mars and the other planets follow elliptical paths. The second says that a planet moves faster when it’s close to the Sun, and slower when it’s farther away. Since Mars is at its maximum distance today, it’s moving at its slowest — a leisurely pace for the Red Planet.

Mars is a third of the way up the western sky at sunset, and looks like a fairly bright orange star. It’s to the upper left of Venus, the brilliant “evening star.”
 

Script by Damond Benningfield

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