A Philosopher Once Asked, "Are We Human Because We Gaze At The Stars, Or Do We Gaze At Them Because We

A philosopher once asked, "Are we human because we gaze at the stars, or do we gaze at them because we are human?" Pointless, really..."Do the stars gaze back?" Now, that's a question.

- Neil Gaiman, Stardust

12 Great Gifts from Astronomy

This is a season where our thoughts turn to others and many exchange gifts with friends and family. For astronomers, our universe is the gift that keeps on giving. We’ve learned so much about it, but every question we answer leads to new things we want to know. Stars, galaxies, planets, black holes … there are endless wonders to study.

In honor of this time of year, let’s count our way through some of our favorite gifts from astronomy.

Our first astronomical gift is … one planet Earth

So far, there is only one planet that we’ve found that has everything needed to support life as we know it — Earth. Even though we’ve discovered over 5,200 planets outside our solar system, none are quite like home. But the search continues with the help of missions like our Transiting Exoplanet Survey Satellite (TESS). And even you (yes, you!) can help in the search with citizen science programs like Planet Hunters TESS and Backyard Worlds.

This animated visualization depicts Earth rotating in front of a black background. Land in shades of tan and green lay among vast blue oceans, with white clouds swirling in the atmosphere. The image is watermarked with the text “Credit: NASA/Goddard Space Flight Center Scientific Visualization Studio” and “visualization.”

Our second astronomical gift is … two giant bubbles

Astronomers found out that our Milky Way galaxy is blowing bubbles — two of them! Each bubble is about 25,000 light-years tall and glows in gamma rays. Scientists using data from our Fermi Gamma-ray Space Telescope discovered these structures in 2010, and we're still learning about them.

This image captures the majestic “Fermi bubbles” that extend above and below our Milky Way galaxy, set against the black background of space. A glowing blue line horizontally crosses the center of the image, showing our perspective from Earth of our galaxy’s spiral arms and the wispy clouds of material above and below it. Cloudy bubbles, colored deep magenta to represent Fermi’s gamma-ray vision, extend above and below the galactic plane. These bubbles are enormous, extending roughly half of the Milky Way's diameter and filling much of the top and bottom of the image. The image is watermarked “Credit: NASA/DOE/Fermi LAT Collaboration.”

Our third astronomical gift is … three types of black holes

Most black holes fit into two size categories: stellar-mass goes up to hundreds of Suns, and supermassive starts at hundreds of thousands of Suns. But what happens between those two? Where are the midsize ones? With the help of NASA’s Hubble Space Telescope, scientists found the best evidence yet for that third, in between type that we call intermediate-mass black holes. The masses of these black holes should range from around a hundred to hundreds of thousands of times the Sun’s mass. The hunt continues for these elusive black holes.

This cartoon depicts two black holes as birds, with a small one representing a stellar-mass black hole on the left and an enormous one representing a supermassive black hole on the right. These two birds appear on a tan background and flap their wings, and then a circle with three question marks pops up between them to represent the intermediate-mass black holes that scientists are hunting for. The image is watermarked “Credit: NASA’s Goddard Space Flight Center.”

Our fourth and fifth astronomical gifts are … Stephan’s Quintet

When looking at this stunning image of Stephan’s Quintet from our James Webb Space Telescope, it seems like five galaxies are hanging around one another — but did you know that one of the galaxies is much closer than the others? Four of the five galaxies are hanging out together about 290 million light-years away, but the fifth and leftmost galaxy in the image below — called NGC 7320 — is actually closer to Earth at just 40 million light-years away.

$A group of five galaxies that appear close to each other in the sky: two in the middle, one toward the top, one to the upper left, and one toward the bottom. Four of the five appear to be touching. One is somewhat separated. In the image, the galaxies are large relative to the hundreds of much smaller (more distant) galaxies in the background. All five galaxies have bright white cores. Each has a slightly different size, shape, structure, and coloring. Scattered across the image, in front of the galaxies are a number of foreground stars with diffraction spikes: bright white points, each with eight bright lines radiating out from the center. The image is watermarked with the text “Credits: NASA, ESA, CSA, and STScI.”$

Our sixth astronomical gift is … an eclipsing six-star system

Astronomers found a six-star system where all of the stars undergo eclipses, using data from our TESS mission, a supercomputer, and automated eclipse-identifying software. The system, called TYC 7037-89-1, is located 1,900 light-years away in the constellation Eridanus and the first of its kind we’ve found.

This diagram shows the sextuple star system TYC 7037-89-1, a group of six stars that interact with each other in complex orbits. The stars are arranged in pairs: System A, System B, and System C, each of which is shown as having one larger white star and one smaller yellow star. The two stars of System A, in the upper left, are connected by a red oval and labeled "1.3-day orbit." The two stars of System C, just below System A, are connected by a turquoise oval and labeled "1.6-day orbit." Additionally, these two systems orbit each other, shown as a larger blue oval connecting the two and labeled "A and C orbit every 4 years." On the other side of the image, in the bottom right, the two stars of System B are connected by a green oval and labeled "8.2-day orbit." Lastly, Systems A, B and C all interact with System B orbiting the combined A-C system, shown as a very large lilac oval labeled "AC and B orbit every 2,000 years." A caption at the bottom of the image notes, "Star sizes are to scale, orbits are not." The image is watermarked with the text “Illustration” and “Credit: NASA's Goddard Space Flight Center.”

Our seventh astronomical gift is … seven Earth-sized planets

In 2017, our now-retired Spitzer Space Telescope helped find seven Earth-size planets around TRAPPIST-1. It remains the largest batch of Earth-size worlds found around a single star and the most rocky planets found in one star’s habitable zone, the range of distances where conditions may be just right to allow the presence of liquid water on a planet’s surface.

Further research has helped us understand the planets’ densities, atmospheres, and more!

his animated image shows an artist's concept of the star TRAPPIST-1, an ultra-cool dwarf, and the seven Earth-size planets orbiting it. TRAPPIST-1 is large and glows bright orange, while the planets are smaller and in shades of cool gray-blue. The image is highly stylized to look like glowing balls sitting on a shiny surface, and neither the sizes nor distances are to scale. The planets closer to TRAPPIST-1 have droplets of water standing on the surface around them, indicating that they may have liquid water. Planets further away have frost around them, indicating that those are more likely to have significant amounts of ice, especially on the side that faces away from the star. Our view pans across the system, from the center outward, and faint tan rings depict the orbits of each planet. The image is watermarked with the text “Illustration” and “Credit: NASA/JPL-Caltech/R. Hurt (IPAC).”

Our eighth astronomical gift is … an (almost) eight-foot mirror

The primary mirror on our Nancy Grace Roman Space Telescope is approximately eight feet in diameter, similar to our Hubble Space Telescope. But Roman can survey large regions of the sky over 1,000 times faster, allowing it to hunt for thousands of exoplanets and measure light from a billion galaxies.

Our ninth astronomical gift is … a kilonova nine days later

In 2017, the National Science Foundation (NSF)’s Laser Interferometer Gravitational-Wave Observatory (LIGO) and European Gravitational Observatory’s Virgo detected gravitational waves from a pair of colliding neutron stars. Less than two seconds later, our telescopes detected a burst of gamma rays from the same event. It was the first time light and gravitational waves were seen from the same cosmic source. But then nine days later, astronomers saw X-ray light produced in jets in the collision’s aftermath. This later emission is called a kilonova, and it helped astronomers understand what the slower-moving material is made of.

This animated illustration shows what happened in the nine days following a neutron star merger known as GW170817, detected on Aug. 17, 2017. In the first part of the animation, a pair of glowing blue neutron stars spiral quickly towards each other and merge with a bright flash. The merger creates gravitational waves (shown as pale arcs rippling out from the center), a near-light-speed jet that produced gamma rays (shown as brown cones and a rapidly-traveling magenta glow erupting from the center of the collision), and a donut-shaped ring of expanding blue debris around the center of the explosion. A variety of colors represent the many wavelengths of light produced by the kilonova, creating violet to blue-white to red bursts at the top and bottom of the collision. In the second part of the animation, we see the collision as it would appear from Earth, looking like a burst of red light in the lower left and a huge umbrella-shaped cascade of blue light in the upper right, representing X-rays. The image is watermarked with the text “Credit: NASA's Goddard Space Flight Center/CI Lab” and “Illustration.”

Our tenth astronomical gift is … NuSTAR’s ten-meter-long mast

Our NuSTAR X-ray observatory is the first space telescope able to focus on high-energy X-rays. Its ten-meter-long (33 foot) mast, which deployed shortly after launch, puts NuSTAR’s detectors at the perfect distance from its reflective optics to focus X-rays. NuSTAR recently celebrated 10 years since its launch in 2012.

This animation shows an artist’s concept of the NuSTAR X-ray observatory orbiting above the blue marble of Earth and deploying its 10-meter-long (33 foot) mast shortly after launch in 2012. NuSTAR is roughly cylindrical, with a shiny silver covering and a pair of blue solar panels on each of its sides. As we pan around the spacecraft, silver scaffolding extends from inside, separating the ends of the telescope to the right distance to begin observing the universe in X-rays. The image is watermarked with the text “Illustration” and “Credit: Credit: NASA/JPL-Caltech.”

Our eleventh astronomical gift is … eleven days of observations

How long did our Hubble Space Telescope stare at a seemingly empty patch of sky to discover it was full of thousands of faint galaxies? More than 11 days of observations came together to capture this amazing image — that’s about 1 million seconds spread over 400 orbits around Earth!

This animated image zooms into the Hubble Ultra Deep Field, showing how a tiny patch of “empty” sky turned out to contain about 10,000 galaxies. The sequence begins with a starry backdrop, then we begin to zoom into the center of this image. As we travel, larger and brighter objects come into view, including dazzling spiral and elliptical galaxies in reds, oranges, blues, and purples. The image is watermarked with the text “Credit: NASA, G. Bacon and Z. Levay (STScI).”

Our twelfth astronomical gift is … a twelve-kilometer radius

Pulsars are collapsed stellar cores that pack the mass of our Sun into a whirling city-sized ball, compressing matter to its limits. Our NICER telescope aboard the International Space Station helped us precisely measure one called J0030 and found it had a radius of about twelve kilometers — roughly the size of Chicago! This discovery has expanded our understanding of pulsars with the most precise and reliable size measurements of any to date.

In this simulation of a pulsar’s magnetic fields, dozens of thin lines dance around a central gray sphere, which is the collapsed core of a dead massive star. Some of these lines, colored orange, form loops on the surface of the sphere. Others, colored blue, arc away from two spots on the lower half of the sphere and vanish into the black background. The image is watermarked with the text “Simulation” and “Credit: NASA's Goddard Space Flight Center.”

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2 years ago

WHAT IS A NEUTRINO??

Blog#123

Wednesday, September 15th, 2021

Welcome back,

Neutrinos are elusive subatomic particles created in a wide variety of nuclear processes. Their name, which means “little neutral one,” refers to the fact that they carry no electrical charge. Of the four fundamental forces in the universe, neutrinos only interact with two — gravity and the weak force, which is responsible for the radioactive decay of atoms. Having nearly no mass, they zip through the cosmos at almost the speed of light.

Countless neutrinos came into existence fractions of a second after the Big Bang. And new neutrinos are created all the time: in the nuclear hearts of stars, in particle accelerators and atomic reactors on Earth, during the explosive collapse of supernovas and when radioactive elements decay. This means that there are, on average, 1 billion times more neutrinos than protons in the universe, according to physicist Karsten Heeger of Yale University in New Haven, Connecticut.

Despite their ubiquity, neutrinos largely remain a mystery to physicists because the particles are so tough to catch. Neutrinos stream through most matter as if they were light rays going through a transparent window, scarcely interacting with everything else in existence. Approximately 100 billion neutrinos are passing through every square centimeter of your body at this moment, though you won’t feel a thing.

Neutrinos were first posited as the answer to a scientific enigma. In the late 19th century, researchers were puzzling over a phenomenon known as beta decay, in which the nucleus inside an atom spontaneously emits an electron. Beta decay seemed to violate two fundamental physical laws: conservation of energy and conservation of momentum. In beta decay, the final configuration of particles seemed to have slightly too little energy, and the proton was standing still rather than being knocked in the opposite direction of the electron. It wasn’t until 1930 that physicist Wolfgang Pauli proposed the idea that an extra particle might be flying out of the nucleus, carrying with it the missing energy and momentum.

“I have done a terrible thing. I have postulated a particle that cannot be detected,“ Pauli said to a friend, referring to the fact that his hypothesized neutrino was so ghostly that it would barely interact with anything and would have little to no mass.

More than a quarter century later, physicists Clyde Cowan and Frederick Reines built a neutrino detector and placed it outside the nuclear reactor at the atomic Savannah River power plant in South Carolina. Their experiment managed to snag a few of the hundreds of trillions of neutrinos that were flying from the reactor, and Cowan and Reines proudly sent Pauli a telegram to inform him of their confirmation. Reines would go on to win the Nobel Prize in Physics in 1995 — by which time, Cowan had died.

But since then, neutrinos have continually defied scientists’ expectations.

The sun produces colossal numbers of neutrinos that bombard the Earth. In the mid-20th century, researchers built detectors to search for these neutrinos, but their experiments kept showing a discrepancy, detecting only about one-third of the neutrinos that had been predicted. Either something was wrong with astronomers’ models of the sun, or something strange was going on.

Physicists eventually realized that neutrinos likely come in three different flavors, or types. The ordinary neutrino is called the electron neutrino, but two other flavors also exist: a muon neutrino and a tau neutrino.

As they pass through the distance between the sun and our planet, neutrinos are oscillating between these three types, which is why those early experiments — which had only been designed to search for one flavor — kept missing two-thirds of their total number.

But only particles that have mass can undergo this oscillation, contradicting earlier ideas that neutrinos were massless. While scientists still don’t know the exact masses of all three neutrinos, experiments have determined that the heaviest of them must be at least 0.0000059 times smaller than the mass of the electron.