First Look At The 2024 Total Solar Eclipse

Ask Ethan: Why Are There Only Three Generations Of Particles?

“It is eminently possible that there are more particles out there than the Standard Model, as we know it, presently predicts. In fact, given all the components of the Universe that aren’t accounted for in the Standard Model, from dark matter to dark energy to inflation to the origin of the matter-antimatter asymmetry, it’s practically unreasonable to conclude that there aren’t additional particles.

But if the additional particles fit into the structure of the Standard Model as an additional generation, there are tremendous constraints. They could not have been created in great abundance during the early Universe. None of them can be less massive than 45.6 GeV/c^2. And they could not imprint an observable signature on the cosmic microwave background or in the abundance of the light elements.

Experimental results are the way we learn about the Universe, but the way those results fit into our most successful theoretical frameworks is how we conclude what else does and doesn’t exist in our Universe. Unless a future accelerator result surprises us tremendously, three generations is all we get: no more, no less, and nobody knows why.”

There are three generations of (fermionic) particles in the Universe. In addition to the lightest quarks (up and down), the electron and positron, and the electron neutrino and anti-neutrino, there are two extra, heavy “copies” of this structure. The charm-and-strange quarks plus the top-and-bottom quarks fill the remaining generations of quarks, while the muon and muon neutrino and anti-neutrino plus the tau and tau neutrino and anti-neutrino comprise the next generation of leptons.

Theoretically, there’s nothing demanding three and only three generations, but experiments have shown that there are no more to within absurd constraints. Here’s the full story of how we know there are only three generations.

Why 2020 Might Be The Best Geminid Meteor Shower Of All-Time

“As the large parent body of the Geminids, asteroid 3200 Phaethon, continues on its tight orbit around the Sun, it will continue to expel matter and be torn apart, bit by tiny bit. The asteroid is about the size of the one that struck Earth 65 million years ago, causing our last great mass extinction. But instead of colliding with us all at once, this ~6 km wide asteroid is slowly dissipating in the presence of the Sun, creating tails of matter and ions but also an ever-thickening debris stream.

With each mid-December that rolls past, Earth slams through that debris stream, creating a show that gets progressively more spectacular with each set of orbits that regularly tick by. Over the past 15 years, the Geminids have regularly been one of the two best displays of meteor showers on Earth, and it’s eminently possible that 2020 will set a new record. The Moon, the Earth, and all of the other predictable conditions are just right for a spectacular show. If the clouds cooperate on December 13 and 14, treat yourself to the greatest natural show of the year. With all that 2020 has brought us, we can all use a cosmic treat like this one.”

Can everyone just have a good thing to enjoy? Can we all just have something nice that we don’t have to fight over? Well, nature might deliver what humanity has been unable to bring us for 2020: a natural show that can’t be stopped by anything, except for clouds. 

Get your Geminid fix today, and then look up on December 13/14 to fully enjoy the show!

(Source)

Hostile and Closed Environments, Hazards at Close Quarters

A human journey to Mars, at first glance, offers an inexhaustible amount of complexities. To bring a mission to the Red Planet from fiction to fact, NASA’s Human Research Program has organized some of the hazards astronauts will encounter on a continual basis into five classifications.

A spacecraft is not only a home, it’s also a machine. NASA understands that the ecosystem inside a vehicle plays a big role in everyday astronaut life.

Important habitability factors include temperature, pressure, lighting, noise, and quantity of space. It’s essential that astronauts are getting the requisite food, sleep and exercise needed to stay healthy and happy. The space environment introduces challenges not faced on Earth.

Technology, as often is the case with out-of-this-world exploration, comes to the rescue! Technology plays a big role in creating a habitable home in a harsh environment and monitoring some of the environmental conditions.

Astronauts are also asked to provide feedback about their living environment, including physical impressions and sensations so that the evolution of spacecraft can continue addressing the needs of humans in space.

Exploration to the Moon and Mars will expose astronauts to five known hazards of spaceflight, including hostile and closed environments, like the closed environment of the vehicle itself. To learn more, and find out what NASA’s Human Research Program is doing to protect humans in space, check out the “Hazards of Human Spaceflight“ website. Or, check out this week’s episode of “Houston We Have a Podcast,” in which host Gary Jordan further dives into the threat of hostile and closed environments with Brian Crucian, NASA immunologist at the Johnson Space Center.

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Not Only Didn’t We Find Water On An Earth-Like Exoplanet, But We Can’t With Current Technology

“Over the past few decades, astronomers have uncovered thousands of new exoplanets. Some of them are rocky; some are temperate; some have water. However, the idea that exoplanet K2-18b is rocky, Earth-like, and has liquid water is absurd, despite recent headlines. Light filters through K2-18b’s atmosphere when it passes in front of its star, enabling us to measure what’s absorbed. Based on those absorption lines, the presence of many chemicals can be inferred, including water. K2-18b is, truly, the first known habitable-zone exoplanet to contain water. However, it is not rocky; its mass and radius are too large, necessitating a large gas envelope around it.”

How incredible was that report that came out last week: the first Earth-like, rocky exoplanet with liquid water on its surface has been discovered! If it were true, it would be incredible. Well, what we did find is still pretty remarkable, but it’s very different from what you’ve likely heard.

We did find water on the exoplanet in question, K2-18b, but only in the vapor phase and only in the atmosphere.

The exoplanet is closer to Earth in terms of mass and radius than any other with water on it, but the planet is still too massive and large to be rocky. It must have an envelope of hydrogen and helium, and both have had their presence detected.

If we want to find atmospheric biosignatures around Earth-like worlds, we need better observatories. Let’s build them! Here’s the real story.

The Smoke From a (Not-so) Distant Fire

Flying directly through thick plumes of smoke may seem more harrowing than exciting. But for members of the CAMP2Ex science team, the chance to fly a P-3 Orion straight through clouds of smoke billowing off fires from Borneo this week was too good an opportunity to pass up.

CAMP2Ex stands for the Cloud, Aerosol and Monsoon Processes in the Philippines Experiment. The 2, by the way, is silent.

It’s a field campaign based out of Clark in the Philippines, flying our P-3, a Learjet and collaborating with researchers on the research vessel Sally Ride to understand how tiny particles in the atmosphere affect cloud formations and monsoon season.

The tiny aerosol particles we’re looking at don’t just come from smoke. Aerosol particles also come from pollution, billowing dust and sea salt from the ocean. They can have an outsized effect on weather and climate, seeding clouds that bring rain and altering how the atmosphere absorbs the Sun’s heat.

The smoke we were flying Monday came from peat fires, burning through the soil. That’s pretty unusual — the last time Borneo had these kind of fires was in 2015, so it was a rare opportunity to sample the chemistry of the smoke and find out what’s mixing with the air.

The planes are loaded with instruments to learn more about aerosol particles and the makeup of clouds, like this high-speed camera that captures images of the particles in flight. 

One instrument on the plane collects droplets of cloud water as the plane flies through them, and on the ground, we test how acidic and what kind of particles form the cloud drops. 

All of these measurements are tools in improving our understanding of the interaction between particles in the air and clouds, rainfall and precipitation in the Pacific Ocean.

Learn more about the CAMP2Ex field campaign, here! 

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Mis conversaciones favoritas son aquellas que se tienen con el lápiz y el papel. 

-Zufriedenheit. 

Loving Vincent (2017) dir. Dorota Kobiela, Hugh Welchman

Using All of Our Senses in Space

Today, we and the National Science Foundation (NSF) announced the detection of light and a high-energy cosmic particle that both came from near a black hole billions of trillions of miles from Earth. This discovery is a big step forward in the field of multimessenger astronomy.

But wait — what is multimessenger astronomy? And why is it a big deal?

People learn about different objects through their senses: sight, touch, taste, hearing and smell. Similarly, multimessenger astronomy allows us to study the same astronomical object or event through a variety of “messengers,” which include light of all wavelengths, cosmic ray particles, gravitational waves, and neutrinos — speedy tiny particles that weigh almost nothing and rarely interact with anything. By receiving and combining different pieces of information from these different messengers, we can learn much more about these objects and events than we would from just one.

Lights, Detector, Action!  

Much of what we know about the universe comes just from different wavelengths of light. We study the rotations of galaxies through radio waves and visible light, investigate the eating habits of black holes through X-rays and gamma rays, and peer into dusty star-forming regions through infrared light.

The Fermi Gamma-ray Space Telescope, which recently turned 10, studies the universe by detecting gamma rays — the highest-energy form of light. This allows us to investigate some of the most extreme objects in the universe.

Last fall, Fermi was involved in another multimessenger finding — the very first detection of light and gravitational waves from the same source, two merging neutron stars. In that instance, light and gravitational waves were the messengers that gave us a better understanding of the neutron stars and their explosive merger into a black hole.

Fermi has also advanced our understanding of blazars, which are galaxies with supermassive black holes at their centers. Black holes are famous for drawing material into them. But with blazars, some material near the black hole shoots outward in a pair of fast-moving jets. With blazars, one of those jets points directly at us!

Multimessenger Astronomy is Cool

Today’s announcement combines another pair of messengers. The IceCube Neutrino Observatory lies a mile under the ice in Antarctica and uses the ice itself to detect neutrinos. When IceCube caught a super-high-energy neutrino and traced its origin to a specific area of the sky, they alerted the astronomical community.

Fermi completes a scan of the entire sky about every three hours, monitoring thousands of blazars among all the bright gamma-ray sources it sees. For months it had observed a blazar producing more gamma rays than usual. Flaring is a common characteristic in blazars, so this did not attract special attention. But when the alert from IceCube came through about a neutrino coming from that same patch of sky, and the Fermi data were analyzed, this flare became a big deal!

IceCube, Fermi, and followup observations all link this neutrino to a blazar called TXS 0506+056. This event connects a neutrino to a supermassive black hole for the very first time.  

Why is this such a big deal? And why haven’t we done it before? Detecting a neutrino is hard since it doesn’t interact easily with matter and can travel unaffected great distances through the universe. Neutrinos are passing through you right now and you can’t even feel a thing!

The neat thing about this discovery — and multimessenger astronomy in general — is how much more we can learn by combining observations. This blazar/neutrino connection, for example, tells us that it was protons being accelerated by the blazar’s jet. Our study of blazars, neutrinos, and other objects and events in the universe will continue with many more exciting multimessenger discoveries to come in the future.

Want to know more? Read the story HERE.

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