StarDate

On September 1st of 1859, Richard Carrington was studying the Sun, as he did every day. The British astronomer used a small telescope to project an image of the Sun on a screen. That allowed him to map the dark features known as sunspots.

But on this day, Carrington saw something he’d never seen before. Bright features mingled with the sunspots. They were the first solar flares ever recorded – and still the most powerful. So the outburst is called the Carrington Event in his honor. Carrington also linked the flares to brilliant auroras seen across the globe the following day – the first observations of space weather.

Carrington was born 200 years ago today, in London. He originally studied theology, but became hooked on astronomy. He joined an observatory, but left after a couple of years. He built his own observatory, in Surrey.

Carrington watched the skies both day and night. He compiled star catalogs. And he made the most impressive studies of the Sun to that time, revealing some crucial details about the Sun. For one thing, it rotates faster near its poles than at the equator. For another, during the 11-year sunspot cycle, the spots move from middle latitudes to near the equator.

Carrington eventually had to give up his research. When his father died, he had to take over the family brewery. His health failed as well. He died in 1875 – a pioneer at studying the Sun.

Script by Damond Benningfield

Lightning may flash through the skies of Mars. But don’t expect to see big, jagged streaks like those produced by storms on Earth. Instead, they may be tiny sparks – like fireflies twinkling through a summer evening.

On Earth, lightning is generated by the motions of bits of ice inside clouds. As the particles move past each other, they build up an electric charge. They dis-charge as lightning.

The clouds on Mars are high and thin, so there’s no way for them to make big lightning bolts. But the dust grains that swirl through the Martian atmosphere might generate their own discharges. And two recent studies found evidence of them.

In the first, researchers combed through recordings made by a microphone on the Perseverance rover. They found 55 instances of small “crackling” sounds near the rover. Almost all of them happened during dust storms, or when small dust devils passed the rover.

The scientists decided the most likely explanation for the crackles was tiny discharges – “lightning” bolts about a centimeter long.

In the second study, a team looked at observations made by the MAVEN orbiter. The scientists looked for radio waves produced by lightning, which are different from other types of radio from the planet. They found a single example – a possible flicker in Martian skies.

Even if lightning is small and rare, it could interfere with future Mars landers – perhaps endangering instruments and people on the Red Planet.

Script by Damond Benningfield

Stargazers on Mars might face one of the same challenges that often hampers a night under the stars here on Earth: clouds. A recent study found that clouds on the Red Planet tend to be thicker at night than during the day. They’re thickest in early morning and evening, especially when Mars is coldest.

A fleet of orbiters and landers has been scanning the planet for decades. The probes have told us quite a bit about the Martian climate. The cloud study came from a craft that’s been in orbit since 2021. It watched the clouds both day and night. It amassed the most complete view of the nighttime sky to date.

Another study looked at Martian winds. Researchers used AI to sift through more than two decades of images collected by two orbiters. The program identified more than a thousand dust devils – twisting columns of air that sweep dust high into the sky, such as this one recorded by the Perseverance rover. [dust devil sounds]

Tracking the motions of the little devils allowed scientists to plot the speed and direction of the winds across the whole planet. The study revealed peak wind speeds of almost a hundred miles per hour – far faster than anything ever recorded by instruments on the surface.

These studies and others are helping scientists better understand how the Martian climate works – day and night, in every season.

More about Martian climate tomorrow.

Script by Damond Benningfield

Time is tricky. There’s no “universal” clock ticking along at a constant rate. Instead, every clock in the universe ticks at its own rate, influenced by its motion and by the gravity of the matter around it. Those influences are built into the clocks of GPS satellites; without them, the system would fail within days.

Scientists recently calculated how clocks would tick on Mars – an average of 477 millionths of a second faster per day than clocks on Earth. But as Mars orbits the Sun, that rate varies by up to 226 millionths of a second.

The scientists used Albert Einstein’s theories of gravity and motion. Stronger gravity and faster motion both make a clock move more slowly as seen by an outside observer. The surface gravity of Mars is only about a third as strong as Earth’s. And because the planet is farther from the Sun, it orbits the Sun more slowly.

But Mars’s orbit is more lopsided than Earth’s, so its orbital speed varies more dramatically. The changing distance also alters the gravitational influence of the Sun, as well as that of Earth and the Moon. The researchers incorporated all of these variables – and many others – to figure out the ticking of Martian clocks.

Mars is working its way into the morning sky. It’s quite low in the east during dawn twilight. But the planet will climb a little higher day by day, and will be in good view this summer.

More about Mars tomorrow.

Script by Damond Benningfield

The Moon creeps up on the heart of Leo tonight, the star Regulus. Regulus is close to the upper left of the Moon at nightfall. The Moon will move closer before they set, around 2 a.m. They’ll be closest together as seen from the West Coast.

The star we see as Regulus is called Regulus A. It’s several times bigger and heavier than the Sun, and much brighter. A tiny companion star is so close that it’s impossible to see through the glare.

That duo appears to have two more companions, Regulus B and C. They form their own pair, orbiting each other once every 600 years or so. Regulus B is about 80 percent the size and mass of the Sun, and one-third as bright. Regulus C is a third of the Sun’s mass and size, and just two percent as bright.

Regulus B and C are 79 light-years from Earth – the same distance as Regulus A. And they’re moving through space in the same speed and direction as the brighter star. That suggests that they’re bound to Regulus A. But they’re a long way from it – several thousand times the distance between Earth and the Sun.

So astronomers haven’t watched the system nearly long enough to calculate a mutual orbit for the two pairs of stars. Estimates say it would take more than a hundred-thousand years for them to complete one circuit. So it’s possible that they’re not really bound at all – just a chance alignment at the bright heart of the lion.

Script by Damond Benningfield