A mysterious UFO-shaped cloud baffled skiers when it appeared in the sky over Sweden.

The bizarre cloud floated in the sky over ski resorts Åre and Duved on Thursday, prompting some to speculate that Martians had arrived for a day on the slopes.

Many rushed to take pictures of the unusual phenomenon and posted them on social media. "I thought it was pretty cool," one of them, Elvira Kuper, told broadcaster SVT.

Experts explained it was a so-called lenticular cloud, which forms over mountain peaks when the air is forced to rise as it hits the hillside. As it cools it condenses into a cloud.

Thanks to their peculiar shape, they are often mistaken for UFOs.

You are now free to radiate about the cabin. Airline travelers and pilots face an even higher risk of radiation doses at elevated altitudes than expected, NASA research shows. The study may impact air travel as well as exploration of Mars.

On Friday, NASA scientists released results from their study NASA's Radiation Dosimetry Experiment, or RaD-X. NASA has been sending giant helium-filled weather balloons into the stratosphere and beyond, and the balloons are equipped with instruments that detect cosmic radiation from outer space.

These are the first detailed insights into radiation levels in the magnetosphere, 120,000 feet above Earth, where charged particles are primarily controlled by the planet's magnetic field.

"The measurements, for the first time, were taken at seven different altitudes, where the physics of dosimetry is very different," Chris Mertens, principal investigator of the RaD-X mission, said.

A witness named Ryan recently contacted us about a sighting he had in September of 2016 in Wroughton, England. After hearing a series of strange noises, a group of fifteen UFOs suddenly appeared on the horizon, prompting Ryan and a group of friends to chase the UFOs in their cars for over an hour.

Did you see mysterious lights in the sky over Mesa over the weekend? If so, you're not alone! Viewer Jeremy White sent us video of some lights that he spotted.

He said the lights, which were "bright red like fire" right before he started recording, began to flicker until they vanished. The clip he sent is 1 minute and 14 seconds.

White said he and his wife, who was behind the wheel, drove toward the lights as they tried to figure out what they were seeing.

"We saw what looked like embers from a fire rising straight up into the sky," White wrote in an email to us. "As we started heading down the street, I noticed what we thought were lights from a blaze were not changing pattern and were, in fact, moving in unison.

"While driving, the lights started to move towards our direction and began to pass overhead," he continued. "This is where I started to record as we realized something abnormal was going on."

White said he is sure the lights were not flares or a plane. He also said he heard no noise to indicate the lights were coming from an aircraft.

An unusual cloud formation drew the attention of many Southern California residents Saturday, with some taking to social media to share the rare sight from all over the area.

It was a so-called "hole punch" cloud, or fallstreak hole. These clouds are created by airplanes — specifically the propellers of airplanes, not engine combustion. Here is how they form: The first requirement is the clouds have to be vertically thin. Then a plane must fly through, which creates a big temperature difference. The temperatures beneath the wings of a C-130 airplane, for example, are 14 degrees warmer than the surrounding environment.

This temperature difference and propeller motion creates a dry punch of air falling from the sky, evaporating the clouds beneath. This is always the case, but if the clouds are too thick or the plane is above 20,000 feet, a hole will not occur.


This is why hole punch clouds are fairly rare to see. But when you do get to see them, like Saturday, it's an incredible sight. Here are some of the photos sent to us from NBC4 viewers.

Footage has surfaced showing what appears to be two UFOs over Jerusalem, Israel, filmed at 01:00am local time early on New Year's Day:


Other videos of 'UFOs in Jerusalem' are doing the rounds, claiming to have been shot on the same night; however they all appear to have added sound and visual effects and are thus likely fakes.

This latest UFO sighting comes six years after another, more spectacular, UFO event occurred over the Dome of the Rock in Jerusalem:

Motorists in the city of Omsk in Siberia were treated to the rare phenomenon as the falling space rock crashed to earth. The meteor, which appeared in the Omsk Oblast, appeared to be a massive fireball and was visible for miles. However experts say the flaring object was actually probably small enough to fit in your pocket.

Vladimir Krupko, head of the local planetarium, said: "Most likely it was a small meteorite, the size of a walnut.

"Since it was flying up high in the air, it was visible from other cities as well.

"When it entered the atmosphere it caught fire at about 120 kilometres (74.5 miles) above the ground, and by the time it was 40-60 kilometres (25-37 miles) above the ground the fire had gone out."

Despite there being plenty of larger objects whizzing around our solar system, no large meteorites, which are debris from a comet, asteroid, or meteoroid, are expected for at least 100 years, Mr Krupko said.

Winter storm walked through the city of Fairbanks in Alaska. During its peak, "he left a lot of ice crystals in the air," says a local resident Bernard Marsha. "We saw a beautiful sight — a sun halo, including a double, January 17," he says.

The inner ring — a common 22-degree solar halo, which was formed by passing sunlight through ice crystals in the form of hexagonal prisms. The outer ring — something a little more exotic. "This is the 46-degree halo, explains atmospheric optics expert Les Cowley. — They are more rare than is written in the textbooks and on websites".

And 22-degree and 46-degree halos are formed due to the same ice crystals in the form of hexagonal prisms, but the 46-degree halo is very dim, and they are almost always impossible to see. Therefore, when the outer ring is seen, usually it's some other phenomenon. "Upper tangent arc, halo, — defines Cowley. — They are formed when the hexagonal columnar crystals arranged in a horizontal row in the air, and can impersonate the 46-degree halo."

A pair of researchers affiliated with the Natural History Museum in Chemnitz and Technische Universität Bergakademie Freiberg, both in Germany, has found evidence in ancient tree rings of a solar sunspot cycle millions of years ago similar to the one observed in more modern times. In their paper published in the journal Geology, Ludwig Luthardt and Ronny Rößler describe how they gathered an assortment of petrified tree samples from a region in Germany and used them to count sunspot cycles.

Scientists know that the sun undergoes a sunspot cycle of approximately 11 years—some spots appear, grow cooler and then slowly move toward the equator and eventually disappear—the changes to the sun spots cause changes to the brightness level of the sun—as the level waxes and wanes, plants here on Earth respond, growing more or less in a given year—this can be seen in the width of tree rings. In this new effort, the researchers gathered petrified tree samples from a region of Germany that was covered by lava during a volcanic eruption approximately 290 million years ago (during the Permian period), offering a historical record of sun activity.

The research pair obtained 43 petrified tree specimens (tree-trunk slices) and report that they were able to count 1,917 rings which were preserved well enough to allow for observation under a microscope. Because the trees had all died at the same time, the researchers were able to establish a baseline between them which allowed for comparing tree ring growth between samples over the same time periods—which covered 79 years. Doing so, they report, revealed very clearly a cycle of growth similar to that seen in modern trees, though in this case, it was slightly different. Today the cycle is an average of 11.2 years, back then it was 10.6—close enough, the researchers suggest, to conclude that the sun has been behaving very predictably for at least 290 million years.

It should be noted that not everyone agrees with the theory that sunspot activity leaves such a clear record in tree rings—other factors might be involved such as general global temperature, weather patterns or even outbreaks of insect populations.

More information: Ludwig Luthardt et al. Fossil forest reveals sunspot activity in the early Permian, Geology(2017)

Astronomers have discovered an object in the active galaxy Cygnus A that wasn't there before.

Last week at the American Astronomical Society meeting in Grapevine, Texas, astronomers made an announcement that's caught the interest of several researchers: a very bright something has appeared in a well-known galaxy.

That galaxy is the elliptical Cygnus A. Cygnus A is one of the brightest radio sources in the sky. It lies approximately 800 million light-years from us (redshift of 0.056). In its core sits a supermassive black hole madly eating and cocooned in gas, while two jets shoot out to either side and light up the intergalactic medium. This activity produces the radio radiation that makes Cygnus A so bright.

Using the recently upgraded Karl G. Jansky Very Large Array (VLA) in New Mexico, Rick Perley (NRAO) and colleagues took a gander at Cygnus A — the first time the instrument has looked at the galaxy since 1989. (Apparently astronomers spent so much VLA time observing the galaxy in the 1980s that they didn't feel the need to look again, Perley joked January 6th in his AAS presentation.) The new observations showed a surprise: a new, secondary object just southwest of the central black hole. This object wasn't in the 1989 radio image. Additional, higher-resolution observations with the Very Long Baseline Array also picked up the object, clearly distinct from the galaxy's nucleus. It's roughly 1,300 light-years from the center.

The whatever-it-is is about twice as bright as the brightest known supernova at these frequencies. In fact, it's much brighter than just about any transitory radio signal known, except for accreting supermassive black holes and tidal disruption events, outbursts created when a black hole eats a star.

The team scoured other archives and found the object in 2003 Keck infrared observations and, more iffily, in some images from Hubble. (The object is so red that it doesn't show up well at optical wavelengths, and in this range the space telescope's resolution isn't as good as that of Keck's adaptive optics.)