To be considered Earth-like, a planet must be rocky, roughly Earth-sized and orbiting Sun-like (G-type) stars. It also has to orbit in the habitable zones of its star — the range of distances from a star in which a rocky planet could host liquid water, and potentially life, on its surface.

"My calculations place an upper limit of 0.18 Earth-like planets per G-type star," says UBC researcher Michelle Kunimoto, co-author of the new study in The Astronomical Journal. "Estimating how common different kinds of planets are around different stars can provide important constraints on planet formation and evolution theories, and help optimize future missions dedicated to finding exoplanets."

According to UBC astronomer Jaymie Matthews: "Our Milky Way has as many as 400 billion stars, with seven percent of them being G-type. That means less than six billion stars may have Earth-like planets in our Galaxy."

Previous estimates of the frequency of Earth-like planets range from roughly 0.02 potentially habitable planets per Sun-like star, to more than one per Sun-like star.

A tiny genetic mutation in the SARS coronavirus 2 variant circulating throughout Europe and the United States significantly increases the virus' ability to infect cells, lab experiments performed at Scripps Research show.

"Viruses with this mutation were much more infectious than those without the mutation in the cell culture system we used," says Scripps Research virologist Hyeryun Choe, PhD, senior author of the study.

The mutation had the effect of markedly increasing the number of functional spikes on the viral surface, she adds. Those spikes are what allow the virus to bind to and infect cells.

"The number — or density — of functional spikes on the virus is 4 or 5 times greater due to this mutation," Choe says.

The spikes give the coronavirus its crown-like appearance and enable it to latch onto target cell receptors called ACE2. The mutation, called D614G, provides greater flexibility to the spike's "backbone," explains co-author Michael Farzan, PhD, co-chairman of the Scripps Research Department of Immunology and Microbiology.

Astronomers have long believed that the bright light of novae comes from thermo-nuclear explosions. Now, an international team, including researchers from the University of Copenhagen, has for the first time demonstrated that most of their brightness comes from shockwaves created in a unique and a previously unknown process. The finding ends a decades-old understanding of novae — and may help solve one of the greatest riddles in astrophysics.

Classical novae have been among the most extensively studied astrophysical phenomena since humans first began wondering about twinkling points in the night sky. Yet we continue to learn new things, as evidenced by new research conducted by the University of Copenhagen, among others.

Novae are explosions that occur when a white dwarf star and its companion star in a binary system orbit closer and closer around one another. As the two stars approach, gas from the companion star is stripped away and onto the white dwarf's surface, where it builds up like a gas shell. Eventually, after thousands of years, the piled up gas shell explodes in a nuclear fusion reaction.

For decades, astronomers believed that this thermo-nuclear explosive event is what caused white dwarves to suddenly shine up to a million times brighter — making them appear to be entirely new stars. Hence the name 'nova', meaning 'new' in Latin. But now, for the first time, an international team of researchers has demonstrated that it is the "shock", not the explosion itself, which mainly causes a nova to blaze brightly in the night sky.

"It's a whole new understanding of how a nova works. Indeed, it changes the more than 45-year-old perception that novae only get their light from the nuclear reaction," states Luca Izzo, co-author of the study — now published in Nature Astronomy. Izzo is an astrophysicist and post-doctoral fellow at the University of Copenhagen's Niels Bohr Institute.

The new evidence comes from observations of 'V906 Carina', a nova discovered in 2018 roughly 13,000 light-years from Earth.

Scientists have long been engaged in a debate on what factors impact the growth of mountains - a process quite fascinating for science, albeit lengthy, and often taking billions of years.

A new study claims to have revealed the main driving force behind the growth of mountains, which regulates how big they become.

According to the research published in Nature on 11 June, "megathrust shear force controls mountain height at convergent plate margins", and tectonic forces underneath mountains determine to what dimensions they grow. Thus, for mountains located near tectonic plate collision zones, maximum mountain height is chiefly decided by an equilibrium of forces within Earth's crust, and not by any weathering or erosion on top.

The team of German scientists, led by Armin Dielforder of the Helmholtz Centre Potsdam, the GFZ German Research Centre for Geosciences, Ralf Hetzel of the Institute of Geology and Palaeontology, the University of Münster, and Onno Oncken, Helmholtz Centre Potsdam, the GFZ German Research Centre for Geosciences, analysed the strength of specific plate boundaries and modeled the forces that would be acting on the tectonic plates. In part they used heat flow measurements near the surface as a proxy for the frictional energy that comes into play during the process.

A recent experiment conducted during research into Huntington's disease shows the anesthetic Ketamine may trigger a 'reset' of electrical activity in our brains, providing a possible explanation for the so-called 'K-hole.'

Huntington's disease is an inherited, degenerative neurological disorder that results in the death of brain cells, leading to impaired coordination which can eventually render those living with the condition unable to speak.

In order to better understand this and a host of other neurological diseases and psychiatric conditions, researchers examine the mechanics of our neural pathways and, in particular, their reaction to certain therapeutic medicines, such as ketamine.

Ketamine is an anaesthetic with pain-numbing and dissociative effects, making it a popular medicine as well as a recreational drug. However, recent tests performed on sheep found that when the animals were given high doses, brain activity stopped completely, and almost instantaneously.

The European Space Agency's Trace Gas Orbiter (TGO) spotted an emerald glow in Mars' wispy atmosphere, marking the first time the phenomenon has been spotted on a world beyond Earth, a new study reports.

"One of the brightest emissions seen on Earth stems from night glow. More specifically, from oxygen atoms emitting a particular wavelength of light that has never been seen around another planet," study lead author Jean-Claude Gérard, of the Université de Liège in Belgium, said in a statement.

"However, this emission has been predicted to exist at Mars for around 40 years — and, thanks to TGO, we've found it," Gérard said.

A mysterious cloud containing radioactive ruthenium-106, which moved across Europe in autumn 2017, is still bothering Europe's radiation protection entities. Although the activity concentrations were innocuous, they reached up to 100 times the levels of what had been detected over Europe in the aftermath of the Fukushima accident. Since no government has assumed responsibility so far, a military background could not be ruled out.

Researchers at the Leibniz University Hannover and the University of Münster now found out that the cloud did not originate from military sources - but rather from civilian nuclear activities. Hence, the release of ruthenium from a reprocessing plant for nuclear fuels is the most conclusive scenario for explaining the incident in autumn 2017. The study has been published in the journal Nature Communications.

Geophysicists have been puzzling over a gradual weakening of the Earth's magnetic field in an area stretching from Africa to South America, which has resulted in technical disturbances in satellites orbiting Earth.

Scientists have resorted to data from the European Space Agency's (ESA) Swarm constellation to probe the disturbing weakening of Earth's magnetic field in the area known as the "South Atlantic Anomaly".

Jurgen Matzka, from the German Research Centre for Geosciences, and a team of experts from the Swarm Data, Innovation and Science Cluster (DISC) have been using data from ESA's Swarm satellite constellation to identify and measure the different magnetic signals that comprise Earth's magnetic field.

"The new, eastern minimum of the South Atlantic Anomaly has appeared over the last decade and in recent years is developing vigorously. We are very lucky to have the Swarm satellites in orbit to investigate the development of the South Atlantic Anomaly. The challenge now is to understand the processes in Earth's core driving these changes," said Matzka.

As symbols of the perfection of human form, one might consider the Venus de Milo or Michelangelo's David. But those don't show the insides, where exceptional designs can be found. As physiologists gain deeper knowledge at smaller and smaller scales, down to the cellular and molecular levels, they find an abundance of design inspirations. Here are some of the most recent examples that have come to light.

Hair

Scientists at Queensland University have made carbon nanodots out of human hair. Carbon nanodots are "highly luminescent carbon nanomaterial from which flexible light-emitting devices" can be fabricated. To produce the carbon nanodots, "they developed a two-step process that involved breaking down the hairs and then burning them at 240 degrees Celsius." Now isn't that a clever way to put wasted hair to use? Think of all that hair being swept up on the floors of barber shops and beauty salons. Why not make light of it?

SpaceX successfully launched its first rideshare mission into orbit today (June 13), lofting a new batch of 58 Starlink internet satellites along with three small Earth-observation satellites before nailing a Falcon 9 rocket landing at sea.

It was a mostly clear morning, with just a few clouds above the launch pad here at Space Launch Complex 40 at Cape Canaveral Air Force Station in Florida at liftoff. Onlookers were treated to an awesome view in the predawn sky — the glow from the rocket's engines were visible well into the flight as it launched at 5:21 a.m. EDT (0921 GMT).

The exhaust from the rocket was illuminated by the sun, which was just below the horizon. The resulting cloud appeared as a nebula hanging in the sky.

"Liftoff of Falcon 9 and Starlink ocho," a SpaceX launch commentator said, referring to the mission's Starlink 8 in Spanish.

The launch is the second Starlink mission so far this month, with one more on the schedule for no earlier than June 22. SpaceX is taking advantage of its fleet of flight-proven Falcon 9 boosters, with plans of launching a record four times in June.