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--------------------- 2743 - ASTRONOMY - discoveries in astronomy?
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- When we came to Santa Rosa in 1973 our Solar System had 9 planets. Now, we have 8. Those large asteroids that are outside the orbit of Neptune are now called “dwarf planets“, not planets. In 1973 astronomers had discovered 32 moons in our Solar System. Today the count is over 150 moons. Here is 50 years of astronomy. Maybe one of my grandkids will write a review for the next 50 years. Just imagine what that could be like?
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- The biggest change is the discovery of planets outside our own Solar System. Astronomers have discovered over 3,000 planets orbiting other suns, other stars, in other solar systems.
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- Living inside our Milky Way Galaxy, 26,000 lightyears form the center, has made it difficult to see what our Milky Way really looks like. We knew it was a spiral galaxy, like Andromeda. But, dust and gas clouds block our visible light so much we can not see enough to get the big picture.
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- What has changed is the telescopes we have above our atmosphere can see in the infrared, X-ray, and Gamma Ray wavelengths. With these new eyes we can see through to the Black Hole in the center and , most recently, we can see a “bar” of stars extending 27,000 lightyears from the center at a 45 degree angle from our line of sight to the center. The Milky Way is a “barred” spiral galaxy with only 2 arms, not 4 arms.
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- In 1973 we knew the Milky Way was part of a Local Group of 24 galaxies. Our neighbor, the Andromeda Galaxy, was the biggest. Since then we have discovered 24 more “ dwarf galaxies”. Our Local Group now has 48 galaxies gravitationally bound together.
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- We now know that this Local Group of galaxies is racing towards another group, the Virgo Cluster of 1,000 galaxies. These two groups of galaxies are approaching each other at 1 million miles per hour.
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- It does not stop there. The Virgo Cluster of galaxies, including us, are hurtling toward the “Great Attractor” at 13 million miles per hour. The Great Attractor is a massive super cluster of 100,000 galaxies that lie some 250 million lightyears from us.
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- One of the galaxies in our Local Group is the Large Megellanic Cloud galaxy. It is 160,000 lightyears from us. In 1987 a supernova exploded in this galaxy allowing astronomers to study a supernova up close.
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- Within 24 hours after the sighting 1,000,000,000,000,000,000,000,000,000 neutrinos passed through the Earth. Neutrinos carry 90% of the energy away in a supernova explosion. Our detectors were able to capture 24 of these neutrinos.
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- This study confirmed for astronomers that a supernova is formed when the star’s core collapses. The expanding shockwave lights up the gaseous ring that was earlier expelled by the star. It is the brightest object in the galaxy but neutrinos are carrying away 100 times more energy than the energy of visible light that we can see.
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- Gamma Ray telescopes were first launched in the 1960’s. Astronomers were surprised when gamma ray burst were discovered every day, coming from all directions in the sky.
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- In 1997 they finally detected a burst that had an X-ray afterglow so they could finally see where the burst was coming from. The bursts themselves only last milliseconds up to a few minutes. The X-ray source was determined to be a distant galaxy (GRB970228) that was several billion lightyears away. The theories are that the bursts are caused by massive stars exploding into intense supernovae. The shortest burst are thought to be neutron stars that collapse into Black Holes.
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- Black Holes have existed in theory since 1967, but, we waited for the Hubble telescope in the 1990’s to first detect them in the cores of many galaxies. All of these galaxies had their innermost stars orbiting about the center at speeds requiring the center mass to be in the millions, or billions, Solar Mass. That much mass in that little space had to be a Black Hole.
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- For example, Galaxy M84 had swirling gas redshifted on one side moving away from us and blueshifted on the other side moving toward us. From these measurements astronomers could calculate the orbiting speed of the orbiting gas. It was moving at 1 million miles per hour. The center mass was calculated to be, at least, 300 million Solar Mass. It was a Black Hole.
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- The Cosmic Microwave Background was discovered in the 1960’s. Spacecraft that have studied this microwave energy have improved to the degree to detect slight variations in the background energy that match the cosmic galactic structure we see today.
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- These studies have given full support of the theory for the Big Bang beginning of the Universe and the early Inflation era that created its homogeneous and isotropic character. The study has accurately calculated the age of the Universe to be 13,700,000,000 years.
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- The biggest discovery has to be that the Universe is expanding at an every increasing rate. There must exist another repulsive force that is counteracting gravity. This discovery came from the Hubble’s Deep Field sighting of Supernova 2002dd that was a distance of 8 billion lightyears. Dozens of these supernovae Type 1a have been sighted all confirming that the expansion of the Universe is accelerating.
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- Hubble’s discovery of gravitational lensing has allowed measurements of the massive halos around galaxies. Studies have confirmed the existence of this Dark Matter that is 23% of the density of the Universe and the Dark Energy accelerating the expansion is 72% of the density of the Universe.
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- All of this created at the time of the Big Bang and we do not know what it is. The parts that we have been discovering is only 5 % of the Universe. The challenge remains for astronomy to discover what is today unobservable in that 95% of dark matter and dark energy.
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In 2010 the Deep Impact spacecraft was chasing down a second comet after it had already observed one. After Deep Impact visited “Comet Temple 1” in 2005, NASA realized the spacecraft still had enough fuel to visit another comet as well. 2.9 billion extra miles (4.6 billion kilometers) later, it met up with “Comet Hartley 2“.
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- To researchers' surprise, the peanut-shaped comet was actually quite active, spewing cyanide-laced gas from its surface. This extra flyby made Deep Impact the first spacecraft to visit two comets in one mission.
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- In 2010, the Sun began to wake up, with some extremely powerful solar flares! The Sun goes through 11-year cycles of solar activity, and a particularly weak cycle came to an end in 2010. The result was that the sun began to exhibit powerful solar activity, which continued into 2011. These solar flares and eruptions can create dazzling aurora displays.
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- After a 6.5-year journey, NASA announced in 2011 that the “Messenger Spacecraft” had safely entered into orbit around the planet Mercury. The completion of this tricky maneuver made Messenger the first artificial satellite to orbit Mercury. From this perch it collected data on the planet's geology, composition and thin atmosphere.
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- In another milestone arrival, NASA's “Dawn Spacecraft” reached the asteroid belt between Mars and Jupiter to observe one of its largest rocks, “Vesta“. The asteroid was one of two stops for the spacecraft, which launched in 2007.
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- From some of Dawn's initial observations in 2011 scientists learned that this huge space rock had a battered surface, sporting mountain ranges and deep craters. The overall aim of the visit was to gather near-global visible and infrared images of Vesta in order to learn more about asteroid topology and composition.
- We said goodbye to “Voyager 1” in 2012. The spacecraft, which originally launched in 1977, finally passed beyond the influence of our sun and entered interstellar space in 2012. During its decades-long mission, the spacecraft sent back breathtaking photos of our solar system, including the famous "Pale Blue Dot" photograph it took in 1990.
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- After it surpassed the “Pioneer 1” spacecraft, Voyager 1 clocked the most distance traveled in space by any human-made object. The spacecraft continues to relay data from its cosmic journey back to Earth even in 2020.
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- Originally dubbed the "comet of the century" due to its anticipated splendor, “Comet ISON” passed by the Sun on November 28, 2013 (American Thanksgiving) and broke apart. Scientists had expected the comet to give off a dazzling light show as a result of what they'd believed to be a large nucleus, but the comet did little more than fade away.
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- The observations were a testament to just how hard comet detection and prediction can be. Upon further observation, scientists concluded that the comet's nucleus might have been much smaller than originally estimated. Nevertheless, the comet's slow approach still allowed scientists to study and learn more about comet behavior before it sizzled away.
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- In February 2013 a 56-foot meteor exploded 930 miles above the city of Chelyabinsk in Russia, just east of Moscow. The explosion, which scientists say was equivalent to that of 470 kilotons of TNT, injured hundreds of people and damaged buildings across the area. Scientists say this impact may have been the most powerful terrestrial meteor impact since a 130-foot object exploded over Siberia in 1908 and flattened 825 square miles of forest.
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- In 2013, scientists were able to identify evidence of cosmic rays on Earth. Because these rays are very difficult to detect, scientists instead relied on observing neutrinos left behind by the rays. Neutrinos themselves are also notoriously hard to detect because they almost never interact with matter, but in the case of these cosmic rays, the “IceCube Observatory” in Antarctica found that they did.
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- The neutrinos, named Bert and Ernie after the Sesame Street characters, significantly more energetic than those produced during an event detected in 1987, but still not powerful enough to provide scientists with definitive information about the origin of the rays. Astrophysicists concluded that top candidates might be a supernova, black hole or gamma ray burst.
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- Touchdown on a comet! In a historic first, the European Space Agency (ESA) visited a comet's surface in 2014. The spacecraft, named the “Philae Lander“, touched down and made brief observations. It was a challenging landing, since the comet was a very small, distant target and the Philae Lander had to make a leap from the larger Rosetta spacecraft, in order to touch down.
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- Unfortunately, Philae bounced into a shadowy area on the comet where it was unable to use its solar panels. The Lander soon slipped into hibernation mode. But before doing so, Philae was able to detect an icy surface on the comet and organic molecules like carbon.
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- In 2014, for the first time ever scientists were able to take an image of our universe's cosmic web. While galaxies seem like the epicenters of our universe, they're actually extremely small compared to all other matter in space. Using light from a quasar as a flashlight, scientists were able to get a better look at these cosmic dust tendrils.
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- The New Horizons spacecraft successfully flew past the icy Dwarf Planet Pluto in 2015. This is the first time we've been able to see Pluto and its moon Charon up close. Notably, scientists discovered that Pluto has an adorable heart on its surface and that it and Charon might actually be more geologically active than scientists first imagined.
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- Where scientists expected to find a pock-marked surface, similar to that of our moon, they instead found a relatively young-looking surface. This smoothness led scientists to believe that the surface may have been reshaped more recently, perhaps by something like ice.
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- In September 2015 scientists confirmed that geysers observed on Saturn's moon Enceladus are evidence of a global ocean inside the moon, not an isolated lake. Scientists were able to determine this based on a slight wobble detected in Enceladus's orbit around Saturn. This discovery, as well as previous discoveries by Cassini of hydrothermal activity on the moon, make Enceladus a prime candidate for future, life-hunting missions in years to come.
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- In 2016 scientists were able to observe for the first time ever evidence of gravitational waves, the wrinkling of space-time that occurs when objects collide. They used a massive laser interferometer called LIGO (Laser Interferometer Gravitational-Wave Observatory) with its twin detectors in Washington and Louisiana. Gravitational waves had been theorized by Einstein but had never been detected before.
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- Scientists detected two sets of gravitational waves in 2016, both triggered by the collisions of black holes millions of years prior that echoed across the universe. These discoveries would go on to win the Nobel Prize for physics in 2017.
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- In another strange discovery for the year, the Hubble Space Telescope spotted what appeared to be 125-mile-high geysers of water vapor erupting from the south pole of Jupiter's moon, Europa. Such a geyser was first spotted in 2012, but astronomers thought that observation was a fluke.
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- Scientists have known for a while now that an icy ocean lies beneath Europa's surface, but evidence of geyser eruptions means that it might be possible for probes to directly analyze Europa's water for signs of microbial life. NASA's “Europa Clipper Spacecraft“, slated for launch next decade, will further investigate those possibilities.
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- August 17, 2017 was a life-changing day for astronomers. On that day, scientists observed the collision of two incredibly dense neutron stars, by detecting both gravitational waves and light created in the collision. While this was the fifth time scientists had observed gravitational waves, it was the first time they were able to observe such events through other measurements as well.
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- A massively international effort between observatories in Italy, Chile and a NASA space telescope allowed scientists to chase the gravitational-wave signal across the sky and locate the event using light observations. The team was able to confirm that the collision produced heavy elements, such as gold.
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- Just days later, people gathered at science museums and open spaces on August 21 to observe a once-in-a-century event: the great American solar eclipse. The event crossed the country coast to coast, from Oregon to South Carolina, and ran 70-mile wide swath caught totality.
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- 2017 saw the demise of a beloved mission, Cassini. The spacecraft launched in 1997 to orbit and observe Saturn and its many moons. During its 13 year orbit around Saturn, the spacecraft discovered half a dozen moons, geysers on Enceladus and lakes on Titan, not to mention a treasure trove of beautiful images of the planet.
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- After more than a decade of circling Saturn, Cassini was running out of fuel and its mission team decided to send it out with one last hurrah. The mission came to a fiery conclusion on September 15, 2017, as Cassini purposefully dove into Saturn, burning up in its atmosphere like a meteor. The maneuver kept nearby moons safe from contamination and offered unprecedented close-up observations of the planet.
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- In October 2017 scientists detected the first known alien visitor passing through our solar system. A team of scientists modeled the path of the object, a space rock later named “Oumuamua“, and determined that it didn't originate in our solar system. While scientists have long theorized about how an alien object could come in contact with our solar system, this was the first observation of such an object.
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- After nearly 15 years on the Martian surface, the “Mars Opportunity Rover” finally lost contact with Earth on June 10, 2018, after a planet-wide dust storm caused the rover to retreat into low-power mode. After listening for months for a signal from the rover, the Opportunity team determined the mission complete at the end of January.
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- Opportunity and its twin rover, “Spirit“, landed on Mars in 2004 with a life-expectancy of 90 Martian days; both outlived that timeline. Spirit survived seven years on the Martian surface and Opportunity went on to last nearly 15, traveling a grand total of 26.5 miles across the Red Planet and performing important geological analysis all the while.
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- The same year , 2018, saw the end of another iconic mission, the exoplanet-hunting space telescope “Kepler“. The mission launched in March 2009 to see what kind of planets might be lurking beyond our solar system. While Kepler suffered an early failure in 2013 that effectively ended its initial mission, scientists were able to regain control of the telescope and transition it into a second phase, dubbed K2.
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- By the time that mission ended in November 2018, because the spacecraft didn't have enough fuel, Kepler had discovered 2,682 exoplanets between its two missions. And even now, there are still hundreds more exoplanet candidates identified by the mission but waiting to be confirmed by follow-up observations.
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- Kepler's successor was already up and running after launching in April 2018. Like Kepler, the “Transiting Exoplanet Survey Satellite”, (TESS) is designed to search for exoplanets. It is scanning both hemispheres of the sky during its first two years of operation, which continue into summer 2020. At the end of its first year, TESS had already found 28 confirmed exoplanets, several of which appear to be in the so-called habitable zone, and, 993 potential planets.
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- The James Webb is scheduled to launch in 2021 and will, among other work, examine exoplanet atmospheres to learn more about these potentially habitable worlds. Scientists rang in the new year in 2019 with an incredibly distant flyby. New Horizons flew past a Kuiper Belt object dubbed 2014 MU69 just as the calendar turned over in North America.
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- Now officially called “Arrokoth“, the object is a two-lobed spinning pancake in the cold, dark reaches of outer space. Now, scientists on the team are trying to determine whether the spacecraft has one more flyby left in it.
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- Other spacecraft made incredible space-rock visits this year as well. The Japanese spacecraft Hayabusa2 was orbiting an asteroid called “Ryugu” when the year began; over the course of 2019 it collected several samples, made an artificial crater on Ryugu's surface and turned back to Earth, where it will arrive late next year.
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- A similar asteroid mission from NASA, “OSIRIS-Rex“, spent all year studying its own space rock, “Bennu“, and strategizing how to collect samples from it.
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- So, that brings us to 2020 and there is still a lot more to learn. Stay tuned!
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- May 21, 2020 942 2743
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--------------------- Thursday, May 21, 2020 -------------------------
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