WEBVTT

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<v Speaker 1>Welcome to Bedtime Astronomy. Explore the wonders of the cosmos

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<v Speaker 1>with our soothing Bedtime Astronomy podcast. Each episode offers a

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<v Speaker 1>gentle journey through the stars, planets, and beyond, perfect for

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<v Speaker 1>unwinding after a long day. Let's travel through the mysteries

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<v Speaker 1>of the universe as you drift off into a peaceful

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<v Speaker 1>slumber under the night sky. This week in Astronomy, NASA's

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<v Speaker 1>SPHEREx tracking objects through sound and blazing light from cosmic darkness.

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<v Speaker 1>NASA's SPHEREx begins mapping the invisible universe. NASA's SPHEREx mission

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<v Speaker 1>has officially begun its groundbreaking scientific observations, initiating an ambitious

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<v Speaker 1>effort to map the entire sky in unprecedented detail. Launched

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<v Speaker 1>on March eleventh, the spacecraft spent the first six weeks

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<v Speaker 1>in space undergoing a series of checkouts, calibrations, and system verifications.

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<v Speaker 1>These preparations ensured that SPHEREx, a space based observatory designed

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<v Speaker 1>to observe an infrared light invisible to the human eye,

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<v Speaker 1>would be ready to fulfill its mission to scan the

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<v Speaker 1>cosmos in one hundred and two different infrared wavelengths, producing

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<v Speaker 1>a comprehensive three D map of hundreds of millions of

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<v Speaker 1>galaxies and providing new insights into the origins of the universe,

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<v Speaker 1>the structure of galaxies, and the chemical building blocks of

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<v Speaker 1>life in the Milky Way. As of May first, SPHEREx

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<v Speaker 1>has entered its phase of regular science operations. Over the

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<v Speaker 1>next two years, it is scheduled to take approximately three thousand,

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<v Speaker 1>six hundred images each day, culminating in a vast, digitally

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<v Speaker 1>woven mosaic of the entire sky. This ambitious project will

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<v Speaker 1>produce four complete sky maps during its primary mission, capturing

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<v Speaker 1>cosmic features and structures in exquisite detail. SPHEREx orbits Earth

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<v Speaker 1>about fourteen and a half times a day in a

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<v Speaker 1>polar orara, traveling from north to south and passing over

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<v Speaker 1>both poles. This configuration allows it to systematically cover circular

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<v Speaker 1>strips of the sky each day, and as Earth journeys

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<v Speaker 1>around the Sun, Spherex's vantage point gradually shifts, enabling it

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<v Speaker 1>to view the universe in every direction. Over the course

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<v Speaker 1>of six months. The observatory gathers data using six infrared

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<v Speaker 1>detectors that capture different wavelengths simultaneously, producing what are known

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<v Speaker 1>as exposures. About six hundred per day. Each exposure consists

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<v Speaker 1>of six unique images, and together they represent a spectrum

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<v Speaker 1>of invisible light that holds critical information about the distant

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<v Speaker 1>objects being observed. Instead of traditional thrusters, SPHEREx adjusts its

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<v Speaker 1>orientation using internal reaction wheels, allowing it to shift its

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<v Speaker 1>entire body between exposures with precision and efficiency. One of

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<v Speaker 1>the most striking features of SPHEREx is its ability to

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<v Speaker 1>observe the sky in one one hundred and two colors

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<v Speaker 1>of infrared light, a feat that has never been accomplished before.

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<v Speaker 1>Unlike visible light, infrared light can pass through cosmic dust

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<v Speaker 1>and reveal phenomena that would otherwise remain hidden. This capability

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<v Speaker 1>allows SPHEREx to see into dusty regions of space, like

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<v Speaker 1>the dense interstellar clouds where stars and planetary systems form.

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<v Speaker 1>A striking early image from the telescope, taken at a

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<v Speaker 1>wavelength of three point twenty nine microns, reveals a dusty

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<v Speaker 1>cloud composed of molecules akin to soot or smoke, structures

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<v Speaker 1>that are both visually stunning and scientifically valuable. Spherrex uses

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<v Speaker 1>a method called spectroscopy to analyze the light it collects.

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<v Speaker 1>This technique splits light into its component wavelengths, similar to

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<v Speaker 1>how a prism creates a rainbow. With spectroscopy, scientists can

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<v Speaker 1>determine how far away a galaxy is, allowing them to

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<v Speaker 1>assemble a three dimensional cosmic map instead of a flat,

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<v Speaker 1>tutementional one. This depth of information helps researchers trace the

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<v Speaker 1>expansion history of the universe and uncover the distribution of

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<v Speaker 1>matter on the largest scales. One of the mission's most

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<v Speaker 1>compelling goals is to shed light on cosmic inflation, or

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<v Speaker 1>rapid expansion, that occurred in the first fraction of a

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<v Speaker 1>second after the Big Bang. During this phase, the universe

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<v Speaker 1>expanded faster than the speed of light, going from subatomic

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<v Speaker 1>to cosmological scales in an instant. This dramatic event left

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<v Speaker 1>subtle imprints in the distribution of galaxies, and Spherrex's vast

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<v Speaker 1>sky maps are expected to reveal patterns that will help

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<v Speaker 1>scientists decode this primordial mystery. By observing the largest scales

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<v Speaker 1>of the modern universe, scientists hope to infer what happened

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<v Speaker 1>at the smallest scales during its earliest moments. A poetic

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<v Speaker 1>symmetry between the ancient and the vast beyond exploring the

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<v Speaker 1>origins of the cosmos. Spherrex also investigates the ingredients for

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<v Speaker 1>life within than our own galaxy by analyzing the light

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<v Speaker 1>from interstellar clouds. The mission aims to identify water and

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<v Speaker 1>other essential compounds across a wide range of environments in

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<v Speaker 1>the Milky Way. It is believed that the water found

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<v Speaker 1>on Earth may have originated as frozen molecules on cosmic

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<v Speaker 1>dust grains in the same interstellar cloud that birth the

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<v Speaker 1>Sun's SPHEREx will perform over nine million such observations, allowing

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<v Speaker 1>scientists to study how the chemistry of these materials changes

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<v Speaker 1>with varying conditions, and leading to a better understanding of

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<v Speaker 1>the origins of planetary systems and life friendly environments. SPHEREx

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<v Speaker 1>does not operate in isolation. It is part of a

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<v Speaker 1>broader strategy by NASA to understand the universe, complementing missions

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<v Speaker 1>like the upcoming Nancy Grace Roman Space Telescope. Together, these

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<v Speaker 1>observatories form a coordinated campaign to address some of the

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<v Speaker 1>deepest questions in astrophysics, from the fundamental forces that shape

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<v Speaker 1>the universe to the process is that foster life. In

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<v Speaker 1>its many corners, the mission represents more than a technological milestone.

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<v Speaker 1>It's a fulfillment of over a decade of dedication from

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<v Speaker 1>teams across NASA, academia, and industry. The instrument has performed

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<v Speaker 1>exactly as hoped, meeting expectations with precision and opening the

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<v Speaker 1>door to discoveries both anticipated and unforeseen. Scientists and engineers

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<v Speaker 1>who have long worked toward this goal now watches SPHERICX

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<v Speaker 1>begins to deliver on its promise to illuminate the hidden universe,

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<v Speaker 1>transform our cosmic perspective, and perhaps uncover answers to some

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<v Speaker 1>of the most profound questions about where we come from,

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<v Speaker 1>what we are made of, and how the universe came

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<v Speaker 1>to be. As it is tracking space objects through sound,

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<v Speaker 1>space debris and meteoroids are constantly making their way toward Earth,

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<v Speaker 1>creating a persistent and increasingly significant hazard as they streak

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<v Speaker 1>through the atmosphere at high speeds. Among the tools scientists

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<v Speaker 1>used to monitor these high velocity entries are infrasound sensors,

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<v Speaker 1>special instruments that detect extremely low frequency sounds that human

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<v Speaker 1>errs cannot hear. These sensors have become vital in detecting

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<v Speaker 1>the acoustic signatures of bolides, which are meteoroids that explode

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<v Speaker 1>or fragment dramatically in the sky, releasing large amounts of

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<v Speaker 1>energy that ripple through the atmosphere as infrasound waves. However,

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<v Speaker 1>tracking these events accurately involves more than just picking up

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<v Speaker 1>their sound. A new study has demonstrated the importance of

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<v Speaker 1>factoring in the object's trajectory, especially when it enters Earth's

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<v Speaker 1>atmosphere at a shallow angle. Each year, Earth collects a

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<v Speaker 1>surprising amount of material from space. Thousands of metric tons

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<v Speaker 1>of space dost drift down from the Cosmos, and around

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<v Speaker 1>fifty tons of meteorites crash into the surface annually. Since

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<v Speaker 1>the beginning of the space Age, humanity has added to

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<v Speaker 1>this influx with its own debris space jump, including rocket remnants,

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<v Speaker 1>lost astronaut tools, and decommissioned satellites, hovers in low Earth

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<v Speaker 1>orbit at astonishing speeds, often reaching up to eighteen thousand

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<v Speaker 1>miles per hour. Occasionally, some of these objects return to

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<v Speaker 1>Earth their fiery descent, creating a risk not only to

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<v Speaker 1>technology and infrastructure, but also to human life. However small

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<v Speaker 1>a chance may be when any space object re enters

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<v Speaker 1>the atmosphere, whether a natural meteoroid or a piece of

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<v Speaker 1>artificial debris. Scientists rush to track its trajectory. They need

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<v Speaker 1>to determine not only when and where it will land,

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<v Speaker 1>but also how it will travel through the atmosphere. Some

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<v Speaker 1>may plunge directly downward, while others streak across the sky

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<v Speaker 1>at shallow angles, skimming the atmosphere before coming to rest.

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<v Speaker 1>Understanding this path is crucial for accurate predictions and potentially

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<v Speaker 1>for issuing alerts or planning responses in the rare event

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<v Speaker 1>of a dangerous impact. This challenge has drawn attention from

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<v Speaker 1>researchers like Elizabeth Silber at Sandy and National Laboratories, who

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<v Speaker 1>is presenting our findings at the European Geoscience's Union General Assembly.

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<v Speaker 1>She focuses on how infrasound sensors detect bulllides and how

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<v Speaker 1>their readings are influenced by the angle at which these

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<v Speaker 1>objects enter the atmosphere. Bulllides are not static events. They

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<v Speaker 1>are dynamic, fast moving phenomena. As they barrel through the sky,

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<v Speaker 1>they generate infrasound along their flight path rather than from

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<v Speaker 1>a single stationary point. This creates a sonic footprint more

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<v Speaker 1>like a sweeping boom than a single explosion. In cases

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<v Speaker 1>where the bullid enters steeply at angles greater than sixty degrees,

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<v Speaker 1>the analysis of infrasound signals can reliably reconstruct the trajectory,

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<v Speaker 1>but when these objects enter more horizontally, the signals become

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<v Speaker 1>more complex and harder to interpret. The sound travels across

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<v Speaker 1>longer distances and is picked up from multiple directions by

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<v Speaker 1>different infrasound stations, increasing the uncertainty and determining exactly where

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<v Speaker 1>the object was and where it might land. To dig

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<v Speaker 1>deeper into this problem, Silber used data from a global

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<v Speaker 1>network of infrasound sensors operated by the Comprehensive Test Ban

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<v Speaker 1>Treaty Organization. Although this network is primarily designed to detect

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<v Speaker 1>illicit nuclear tests, it also captures many other loud atmospheric events,

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<v Speaker 1>from lightning to rocket launches. By focusing on bull eyed events,

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<v Speaker 1>Silber was able to isolate the geometric elements of the

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<v Speaker 1>infrasound data, specifically how the movement of the object affected

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<v Speaker 1>the sound's propagation. Her finding stress that trajectory must be

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<v Speaker 1>accounted for if scientists are to interpret the signals correctly,

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<v Speaker 1>particularly for objects with flatter paths. This research underscores a

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<v Speaker 1>larger point about planetary defense and the management of space

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<v Speaker 1>debris Infrasound sensors are an essential part of the global

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<v Speaker 1>toolkit for tracking threats from aboff. However, their effectiveness depends

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<v Speaker 1>on how well we understand and interpret the data they collect.

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<v Speaker 1>If the direction and speed of an incoming object are

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<v Speaker 1>not accurately reconstructed, it becomes much harder to predict its

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<v Speaker 1>landing site or assess the risks. In short, knowing that

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<v Speaker 1>something is coming is not enough. Scientists need to know

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<v Speaker 1>how it's moving in order to respond effectively. This work

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<v Speaker 1>not only advances our ability to monitor meteoroids, but also

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<v Speaker 1>has important implications for the safe management of space junk

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<v Speaker 1>as our skies become increasingly crowded. Blazing light from cosmic darkness.

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<v Speaker 1>Some of the brightest sources of light in the universe

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<v Speaker 1>have their origins in some of the darkest places imaginable,

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<v Speaker 1>the regions surrounding supermassive black holes at the centers of galaxies.

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<v Speaker 1>These brilliant cosmic beacons, which we cannot see with the

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<v Speaker 1>naked eye, emit immense amounts of energy across the electromagnetic spectrum. Satellites,

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<v Speaker 1>particularly NASA's Fermi Gamma Ray Space Telescope have revealed the

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<v Speaker 1>astonishing number and variety of these luminous powerhouses since it

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<v Speaker 1>began its mission in two thousand and eight. Despite their

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<v Speaker 1>association with darkness, black holes helped create some of the

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<v Speaker 1>most powerful light shows in the universe. Fermi's Large Area

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<v Speaker 1>Telescope LAT has cataloged thousands of high energy sources in

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<v Speaker 1>just a single year of observation. Data show hundreds of

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<v Speaker 1>objects flaring and fading in gamma rays, captured in an

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<v Speaker 1>animation where each object's brightness is indicated by the size

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<v Speaker 1>of a glowing magenta circle. The Sun's path is tracked

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<v Speaker 1>two represented by a yellow circle, tracing its annual motion

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<v Speaker 1>across the sky. Over ninety percent of these flashing gamma

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<v Speaker 1>ray sources are what astronomers call blazers, a specific type

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<v Speaker 1>of galaxy powered by supermassive black holes. Supermassive black holes

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<v Speaker 1>are not rare. They lurk at the center of nearly

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<v Speaker 1>every large galaxy, including our own Milky Way. These giants

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<v Speaker 1>range in mass from hundreds of thousands to billions of

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<v Speaker 1>times that of our Sun. While black holes themselves do

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<v Speaker 1>not emit light, they are, after all defined by their

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<v Speaker 1>ability to trap even light what surrounds them. In active

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<v Speaker 1>galaxies can shine intensely. In galaxies with active galactic nuclei

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<v Speaker 1>agn the black hole is surrounded by a dense, swirling

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<v Speaker 1>cloud of gas and dust. As this material spirals inward,

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<v Speaker 1>pulled by gravity, it forms a hot accretion disc. The

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<v Speaker 1>friction and extreme gravitational forces that work heat the disk

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<v Speaker 1>to incredible temperatures, causing it to emit radiation across a

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<v Speaker 1>wide range of wavelengths, from radio waves to X rays

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<v Speaker 1>and gamma rays. This radiation is not the end of

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<v Speaker 1>the story. In about one in ten active galaxies, jets

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<v Speaker 1>of particles are also formed and blasted outward from the

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<v Speaker 1>region near the black hole. These jets travel at speeds

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<v Speaker 1>approaching that of light and extend far beyond the galaxy itself.

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<v Speaker 1>Scientists continue to investigate how black holes, with their overwhelming

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<v Speaker 1>gravity that pulls everything inward, are able to power such

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<v Speaker 1>outward moving high energy jets. The process remains one of

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<v Speaker 1>the more mysterious aspects of black hole physics. The appearance

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<v Speaker 1>and classification of these active galaxies depend heavily on their

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<v Speaker 1>orientation relative to Earth. When we see the jets side on,

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<v Speaker 1>we might classify the galaxy as a radio galaxy since

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<v Speaker 1>the side view reveals strong emissions at radio wavelengths, but

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<v Speaker 1>when the jet is aimed almost directly at us, we

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<v Speaker 1>see a blazer, a galaxy that appears especially bright and

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<v Speaker 1>variable due to the relativistic beaming of light coming from

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<v Speaker 1>its jet. These are the most commonly detected gamma ray

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<v Speaker 1>so in the sky by Fermi. Gamma rays, the most

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<v Speaker 1>energetic form of light, are crucial for astronomers trying to

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<v Speaker 1>understand high energy processes in the universe. They offer insight

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<v Speaker 1>into how particles are accelerated in these extreme environments and

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<v Speaker 1>how they interact with magnetic fields and surrounding material. Since

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<v Speaker 1>two thousand and eight, FERMI has identified thousands of gamma

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<v Speaker 1>ray sources, with blazers making up more than half. Each

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<v Speaker 1>detection adds to the growing picture of the high energy

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<v Speaker 1>universe and the role that AGN play in it. Understanding

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<v Speaker 1>AGN is more than just studying interesting cosmic phenomena. Many

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<v Speaker 1>of these active galaxies formed early in the history of

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<v Speaker 1>the universe. Because of their immense power, they likely played

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<v Speaker 1>a significant role in shaping their environments, influencing the formation

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<v Speaker 1>of galaxies and the evolution of cosmic structures. By studying

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<v Speaker 1>agn scientists hope to uncover the mechanisms that helped shape

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<v Speaker 1>the universe as we know it today. The story of

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<v Speaker 1>the brightest lights in the cosmos is in fact a

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<v Speaker 1>story about how darkness supermassive black holes can generate energy

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<v Speaker 1>on unimaginable scales, revealing the dynamic and ever evolving nature

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<v Speaker 1>of the universe to a