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  • richardmitnick 12:47 pm on March 9, 2020 Permalink | Reply
    Tags: "Magnetic Fields Around NASA's Mars Lander Are 10 Times Stronger Than Scientists Expected", , , , , , , NASA Incite, , Universe Today   

    From Universe Today via Science Alert: “Magnetic Fields Around NASA’s Mars Lander Are 10 Times Stronger Than Scientists Expected” 

    universe-today

    From Universe Today

    via

    ScienceAlert

    Science Alert

    9 MARCH 2020
    MATT WILLIAMS, UNIVERSE TODAY

    1
    NASA Insight (NASA/JPL-Caltech)

    When NASA’s Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (Insight) lander set down on Mars in November of 2018, it began its two-year primary mission of studying Mars’ seismology and interior environment.

    And now, just over a year and a half later, the results of the lander’s first twelve months on the Martian surface have been released in a series of studies.

    One of these studies, which was recently published in the journal Nature Geosciences, shared some rather interesting finds about magnetic fields on Mars.

    According to the research team behind it, the magnetic field within the crater where InSight’s landed is ten times stronger than expected. These findings could help scientists resolve key mysteries about Mars’ formation and subsequent evolution.

    These readings were obtained by InSight’s magnetic sensor, which studied the magnetic fields within the mission’s landing zone. This shallow crater, known as “Homestead hollow”, is located in the region called Elysium Planitia – a flat-smooth plain just north of the equator.

    This region was selected because it has the right combination of flat topology, low elevation, and low debris to allow InSight to probe deep into the interior of Mars.

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    Sources of magnetism detected by magnetic sensor aboard the Mars InSight Lander. (NASA/JPL-Caltech)

    Prior to this mission, the best estimates of Martian magnetic fields came from satellites in orbit and were averaged over distances of more than 150 kilometres (93 miles).

    Catherine Johnson, a professor of Earth, Ocean, and Atmospheric Sciences at the University of British Columbia and a senior scientist at the Planetary Science Institute (PSI), was the lead author on the study. As she said in a recent UBC News story:

    “One of the big unknowns from previous satellite missions was what the magnetization looked like over small areas. By placing the first magnetic sensor at the surface, we have gained valuable new clues about the interior structure and upper atmosphere of Mars that will help us understand how it – and other planets like it – formed.”

    “The ground-level data give us a much more sensitive picture of magnetization over smaller areas, and where it’s coming from. In addition to showing that the magnetic field at the landing site was ten times stronger than the satellites anticipated, the data implied it was coming from nearby sources.”

    Measuring magnetic fields on Mars is key to understanding the nature and strength of the global magnetic field (aka magnetosphere) that Mars had billions of years ago.

    The presence of this magnetosphere has been inferred from the presence of magnetized rocks on the planet’s surface, leading to localized and relatively weak magnetic fields.

    According to data gathered by MAVEN and other missions, scientists predict that roughly 4.2 billion years ago, this magnetic field suddenly ‘switched off’. This resulted in solar wind slowly stripping the Martian atmosphere away over the next few hundred million years, which is what led to the surface becoming the dry and desiccated place it is today.

    Because most rocks on the surface of Mars are too young to have been magnetized by this ancient field, the team thinks it must be coming from deeper underground.

    As Johnson explained:

    “We think it’s coming from much older rocks that are buried anywhere from a couple hundred feet to ten kilometers below ground. We wouldn’t have been able to deduce this without the magnetic data and the geology and seismic information InSight has provided.”

    By combining InSight data with magnetic readings obtained by Martian orbiters in the past, Johnson and her colleagues hope to be able to identify exactly which rocks are magnetized and how old they are.

    These efforts will be bolstered by future missions to study Martian rocks, such as NASA’s Mars 2020 rover, the ESA’s Rosalind Franklin rover, and China’s Huoxing-1 (HX-1) mission – all of which are scheduled to launch this summer.

    Depiction of NASA Mars 2020 Rover officially named “Perseverence”

    ESA/Roscosmos Rosalind Franklin ExoMars rover depiction

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    Huoxing-1 (HX-1) depiction. China

    4
    Artist’s impression of the interaction between solar wind and the planets Mars (left) and Earth (right).(NASA)

    InSight’s magnetometer also managed to gather data on phenomena that exist high in Mars’ upper atmosphere as well as the space environment surrounding the planet.

    Like Earth, Mars is exposed to solar wind, the stream of charged particles that emanate from the Sun and carry its magnetic field into interplanetary space – hence the name interplanetary magnetic field (IMF).

    But since Mars lacks a magnetosphere, it is less protected from solar wind and weather events. This allows the lander to study the effects of both on the surface of the planet, which scientists have been unable to do until now.

    Said Johnson:

    “Because all of our previous observations of Mars have been from the top of its atmosphere or even higher altitudes, we didn’t know whether disturbances in solar wind would propagate to the surface. That’s an important thing to understand for future astronaut missions to Mars.”

    Another interesting find was the way the local magnetic field fluctuated between day and night, not to mention the short pulsations that occurred around midnight and lasted for just a few minutes. Johnson and her colleagues theorize that these are caused by interactions between solar radiation, the IMF, and particles in the upper atmosphere to produce electrical currents (and hence, magnetic fields).

    These readings confirm that events taking place in and above Mars’ upper atmosphere can be detected at the surface. They also provide an indirect picture of the planet’s atmospheric properties, like how charged it becomes and what currents exist in the upper atmosphere.

    As for the mysterious pulses, Johnson and her team are not sure what causes them but think that they are also related to how solar wind interacts with Mars.

    In the future, the InSight team hopes that their efforts to gather data on the surface magnetic field will coincide with the MAVEN orbiter passing overhead, which will allow them to compare data.

    As InSight’s principal investigator, Bruce Banerdt of NASA’s Jet Propulsion Laboratory, summarized:

    The main function of the magnetic sensor was to weed out magnetic ‘noise,’ both from the environment and the lander itself, for our seismic experiments, so this is all bonus information that directly supports the overarching goals of the mission. The time-varying fields, for example, will be very useful for future studies of the deep conductivity structure of Mars, which is related to its internal temperature.”

    This study is one of six that resulted from InSight’s first year of mission data, which can be accessed here. However, this is just the beginning for the InSight mission, which will wrap up its two-year primary mission towards the end of 2020.

    Of particular interest are the X-band radio measurements that will show how much Mars’ “wobbles” as it spins on its axis, which in turn will help reveal the true nature of the planet’s core (solid or liquid?).

    Exciting times lie ahead for the many missions we have (or will be sending) to Mars! Be sure to check out this video of the InSight mission too, courtesy of NASA JPL:

    See the full article here .


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  • richardmitnick 8:32 am on June 17, 2019 Permalink | Reply
    Tags: "This Incredible Orbit Map of Our Solar System Makes Our Brains Ache", Eleanor Lutz, , , Universe Today,   

    From University of Washington via Science Alert: Women in STEM- “This Incredible Orbit Map of Our Solar System Makes Our Brains Ache” Eleanor Lutz 

    U Washington

    From University of Washington

    via

    ScienceAlert

    Science Alert

    1
    (Eleanor Lutz)

    17 JUN 2019
    EVAN GOUGH

    If you want to know what a talent for scientific visualizations looks like, check out Eleanor Lutz. She’s a PhD student in biology at the University of Washington, and at her website Tabletop Whale, you can see her amazing work on full display.

    Her latest piece is a map showing all the orbits of over 18,000 asteroids in the Solar System. It includes 10,000 asteroids that are over 10 km in diameter, and about 8,000 objects of unknown size.

    As the tagline at her website says, she produces “Charts, infographics, and animations about any and all things science.”

    This includes things like a “Visual Compendium of Glowing Creatures,” “All the Stars You Can See From Earth,” and a beautiful topographic map of Mercury.

    2

    But it’s her newest project that is garnering her a lot of attention in the space community. Lutz is working on an Atlas of Space, and has been for the last year and a half. It’s a collection of ten visualizations including planets, moons, and outer space.

    As she says on her website, “I’ve made an animated map of the seasons on Earth, a map of Mars geology, and a map of everything in the solar system bigger than 10 km.”

    It’s that map of objects larger than 10 km that is generating buzz.

    3
    (Eleanor Lutz)

    All of the data for Lutz’s Atlas of Space is public data, freely available. She gets if from sources like NASA and the US Geological Survey.

    Part of what drives her is that even though the data is public and freely available, it’s raw. And taking that raw data and turning it into a helpful, and even beautiful, visualization, takes a lot of work.

    In an interview with Wired, Lutz said, “I really like that all this data is accessible, but it’s very difficult to visualize. It’s really awesome science, and I wanted everyone to be able to see it in a way that makes sense.”

    4
    ( Eleanor Lutz)

    5
    (Eleanor Lutz)

    Lutz’s work is really more than data visualizations. She has a designer’s eye, and some of her work is very artful.

    But being a scientist, she’s inspired to share the data and the methods she used to create her work. She plans to publish the open source code for each of her pieces, and also tutorials for how to create them yourself.

    It’s difficult to understand our world, or anything in nature really, without engaging with science. Without science, all we have is anecdote and opinion.

    But science is all about data, and dense data is not everyone’s cup of tea. It’s taxing and time-consuming to understand.

    Lutz’s work is making it easier. In an interview with Wired, she said, “There’s a knowledge barrier to accessing some of the interesting, awesome things about science. There are so many facts and equations, and I want those cool ideas to be accessible.”

    To access some of those cool ideas she’s talking about, visit her website, tabletopwhale.com, where you can explore her work and her methods. You can also purchase prints there.

    This article was originally published by Universe Today. Read the original article.

    See the full article here .


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    The University of Washington is one of the world’s preeminent public universities. Our impact on individuals, on our region, and on the world is profound — whether we are launching young people into a boundless future or confronting the grand challenges of our time through undaunted research and scholarship. Ranked number 10 in the world in Shanghai Jiao Tong University rankings and educating more than 54,000 students annually, our students and faculty work together to turn ideas into impact and in the process transform lives and our world. For more about our impact on the world, every day.
    So what defines us —the students, faculty and community members at the University of Washington? Above all, it’s our belief in possibility and our unshakable optimism. It’s a connection to others, both near and far. It’s a hunger that pushes us to tackle challenges and pursue progress. It’s the conviction that together we can create a world of good. Join us on the journey.

     
  • richardmitnick 2:05 pm on December 15, 2018 Permalink | Reply
    Tags: , , , , NASA/ESA Hera, NELIOTA-NEO Lunar Impacts and Optical TrAnsients, , Universe Today   

    From Science Alert: “Every Few Hours a Flash of Light Comes From The Moon. Another Impact” 

    ScienceAlert

    From Science Alert

    15 DEC 2018
    MATT WILLIAMS, THE UNIVERSE TODAY

    Ever since the Apollo missions explored the lunar surface, scientists have known that the Moon’s craters are the result of a long history of meteor and asteroid impacts. But it has only been in the past few decades that we have come to understand how regular these are.

    In fact, every few hours, an impact on the lunar surface is indicated by a bright flash. These impact flashes are designed as a “transient lunar phenomena” because they are fleeting.

    Basically, this means that the flashes (while common) last for only a fraction of a second, making them very difficult to detect. For this reason, the European Space Agency (ESA) created the NEO Lunar Impacts and Optical TrAnsients (NELIOTA) project in 2015 to monitor the moon for signs of impact flashes.

    By studying them, the project hopes to learn more about the size and distribution of near-Earth objects to determine if they pose a risk to Earth.

    To be fair, this phenomena is not new to astronomers, as flashes have been reportedly seen lighting up dark sections of the Moon for at least a thousand years.

    It has only been recently, however, that scientists have had telescopes and cameras sophisticated enough to observe these events and characterize them (i.e. size, speed and frequency).

    1
    (NASA/Jennifer Harbaugh)

    Determining how often such events take place, and what they can teach us about our Near-Earth environment is the reason the ESA created NELIOTA.

    In February of 2017, the project began a 22 month-long campaign to observe the Moon using the 1.2 m telescope at the Kryoneri Observatory located in Greece. This telescope is the largest instrument on Earth ever dedicated to monitoring the Moon.

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    Kryoneri Observatory, Greece

    In addition, the NELIOTA system is the first to use a 1.2 m-telescope for monitoring the Moon. Traditionally, lunar monitoring programs have relied on telescopes with primary mirrors measuring 0.5 m in diameter or smaller.

    The larger mirror of the Kryoneri telescope allows the NELIOTA scientists to detect flashes two magnitudes fainter than other lunar monitoring programs.

    But even with the right instruments, detecting these flashes is no easy task. In addition to lasting for only a fraction of a second, it is also impossible to spot them on the bright side of the Moon since the sunlight reflected from the surface is much brighter.

    For this reason, these events can only be seen on the Moon’s “dark side” – i.e. between a New Moon and First Quarter and between a Last Quarter and New Moon.

    The Moon must also be above the horizon at the time and observations must be conducted using a fast-frame camera. Because of these necessary conditions, the NELIOTA project has only been able to obtain 90 hours of observation time over a 22-month period, during which time 55 lunar impact events were observed.

    From this data, scientists were able to extrapolate that an average of about 8 flashes occur every hour on the surface of the Moon.

    3
    (ESA/AFP)

    Another feature that sets the NELIOTA project apart is its two fast-frame cameras that enable lunar monitoring in the visible and near-infrared bands of the spectrum.

    This allowed the project scientists to conduct the first study ever where the temperatures of lunar impacts were calculated. Of the first ten they detected, they obtained temperature estimates ranging from about 1,300 to 2,800 °C ( 2372 to 5072 °F).

    With the extension of this observing campaign to 2021, the NELIOTA scientists hope to obtain further data that will improve impact statistics.

    In turn, this information will go a long way towards addressing the threat of Near-Earth Objects – which consist of asteroids and comets that periodically pass close to Earth (and on rare occasions, impact on the surface).

    In the past, the ESA has monitored these objects through its Space Situational Awareness (SSA) program, of which the NELTIOA project is part.

    Today, the SSA is building infrastructure in space and on the ground (such as the deployment of Flyeye telescopes across the globe) to improve our monitoring and understanding of potentially hazardous NEOs.

    ESA Flyeye telescope

    In the future, the ESA plans to transition from monitoring NEOs to developing mitigation and active planetary defense strategies.

    This includes the proposed NASA/ESA Hera mission – formerly known as the Asteroid Impact & Deflection Assessment (AIDA) – which is scheduled to launch by 2023.

    NASA ESA Hera

    In the coming decades, other measures (ranging from directed energy and ballistic missiles to solar sails) are also likely to be investigated.

    But as always, the key to protecting Earth from future impacts is the existence of effective detection and monitoring strategies. In this respect, projects like NELIOTA will prove to be invaluable.

    See the full article here .


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  • richardmitnick 7:06 am on February 28, 2018 Permalink | Reply
    Tags: , , , , , , Universe Today   

    From Universe Today: “Amazing High Resolution Image of the Core of the Milky Way, a Region with Surprisingly Low Star Formation Compared to Other Galaxies” 

    universe-today

    Universe Today

    27 Feb , 2018
    Matt Williams

    1
    The centre of the Milky Way Galaxy seen through NASA’s Spitzer Space Telescope. http://www.spitzer.caltech.edu/images/1540-ssc2006-02a-A-Cauldron-of-Stars-at-the-Galaxy-s-Center

    NASA/Spitzer Infrared Telescope

    Compared to some other galaxies in our Universe, the Milky Way is a rather subtle character. In fact, there are galaxies that are a thousands times as luminous as the Milky Way, owing to the presence of warm gas in the galaxy’s Central Molecular Zone (CMZ). This gas is heated by massive bursts of star formation that surround the Supermassive Black Hole (SMBH) at the nucleus of the galaxy.

    The core of the Milky Way also has a SMBH (Sagittarius A*) and all the gas it needs to form new stars.

    SgrA* NASA/Chandra

    But for some reason, star formation in our galaxy’s CMZ is less than the average. To address this ongoing mystery, an international team of astronomers conducted a large and comprehensive study of the CMZ to search for answers as to why this might be.

    The study, titled Star formation in a high-pressure environment: an SMA view of the Galactic Centre dust ridge recently appeared in the Monthly Notices of the Royal Astronomical Society. The study was led by Daniel Walker of the Joint ALMA Observatory and the National Astronomical Observatory of Japan, and included members from multiple observatories, universities and research institutes.

    See the full article here .

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  • richardmitnick 9:25 am on February 4, 2018 Permalink | Reply
    Tags: , , , Universe Today   

    From Universe Today: “For the First Time, Planets Have Been Discovered in ANOTHER Galaxy!” 

    universe-today

    Universe Today

    3 Feb , 2018
    Matt Williams

    1
    Using the microlensing metthod, a team of astrophysicists have found the first extra-galactic planets! Credit: NASA/Tim Pyle

    Gravitational microlensing, S. Liebes, Physical Review B, 133 (1964): 835

    The first confirmed discovery of a planet beyond our Solar System (aka. an Extrasolar Planet) was a groundbreaking event. And while the initial discoveries were made using only ground-based observatories, and were therefore few and far between, the study of exoplanets has grown considerably with the deployment of space-based telescopes like the Kepler space telescope.

    As of February 1st, 2018, 3,728 planets have been confirmed in 2,794 systems, with 622 systems having more than one planet. But now, thanks to a new study by a team of astrophysicists from the University of Oklahoma, the first planets beyond our galaxy have been discovered! Using a technique predicting by Einstein’s Theory of General Relativity, this team found evidence of planets in a galaxy roughly 3.8 billion light years away.

    The study which details their discovery, titled Probing Planets in Extragalactic Galaxies Using Quasar Microlensing, recently appeared in The Astrophysical Journal Letters. The study was conducted by Xinyu Dai and Eduardo Guerras, a postdoctoral researcher and professor from the Homer L. Dodge Department of Physics and Astronomy at the University of Oklahoma, respectively.

    See the full article here .

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  • richardmitnick 11:33 am on January 25, 2018 Permalink | Reply
    Tags: , , , , , Π1 Gruis, This is the Surface of a Giant Star 350 Times Larger Than the Sun, Universe Today   

    From Universe Today: “This is the Surface of a Giant Star, 350 Times Larger Than the Sun” 

    universe-today

    Universe Today

    24 Jan , 2018
    Matt Williams

    1
    This artist’s impression shows the red supergiant star. Using ESO’s Very Large Telescope Interferometer, an international team of astronomers have constructed the most detailed image ever of this, or any star other than the Sun. Credit: ESO/M. Kornmesser.

    2009 ESO VLT Interferometer image, Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level

    When it comes to looking beyond our Solar System, astronomers are often forced to theorize about what they don’t know based on what they do. In short, they have to rely on what we have learned studying the Sun and the planets from our own Solar System in order to make educated guesses about how other star systems and their respective bodies formed and evolved.

    For example, astronomers have learned much from our Sun about how convection plays a major role in the life of stars. Until now, they have not been able to conduct detailed studies of the surfaces of other stars because of their distances and obscuring factors. However, in a historic first, an international team of scientists recently created the first detailed images of the surface of a red giant star located roughly 530 light-years away.

    The study recently appeared in the scientific journal Nature under the title Large Granulation cells on the surface of the giant star Π¹ Gruis. The study was led by Claudia Paladini of the Université libre de Bruxelles and included members from the European Southern Observatory, the Université de Nice Sophia-Antipolis, Georgia State University, the Université Grenoble Alpes, Uppsala University, the University of Vienna, and the University of Exeter.

    For the sake of their study, the team used the Precision Integrated-Optics Near-infrared Imaging ExpeRiment (PIONIER) instrument on the ESO’s Very Large Telescope Interferometer (VLTI) to observe the star known as Π¹ Gruis.

    ESO VLTI PIONIER instrument [First light October 2010]

    Located 530 light-years from Earth in the constellation of Grus (The Crane), Π1 Gruis is a cool red giant. While it is the same mass as our Sun, it is 350 times larger and several thousand times as bright.

    See the full article here .

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  • richardmitnick 8:57 am on January 20, 2018 Permalink | Reply
    Tags: A Black Hole is Pushing the Stars Around in this Globular Cluster, , , , , Universe Today   

    From Universe Today: “A Black Hole is Pushing the Stars Around in this Globular Cluster” 

    universe-today

    Universe Today

    19 Jan , 2018
    Matt Williams

    1
    Artist’s impression of the star cluster NGC 3201 orbiting an black hole with about four times the mass of the Sun. Credit: ESO/L. Calçada

    Astronomers have been fascinated with globular clusters ever since they were first observed in 17th century. These spherical collections of stars are among the oldest known stellar systems in the Universe, dating back to the early Universe when galaxies were just beginning to grow and evolve. Such clusters orbit the centers of most galaxies, with over 150 known to belong to the Milky Way alone.

    One of these clusters is known as NGC 3201, a cluster located about 16,300 light years away in the southern constellation of Vela. Using the ESO’s Very Large Telescope (VLT) at the Paranal Observatory in Chile, a team of astronomers recently studied this cluster and noticed something very interesting. According to the study they released, this cluster appears to have a black hole embedded in it.

    ESO VLT Platform at Cerro Paranal elevation 2,635 m (8,645 ft)

    The study appeared in the Monthly Notices of the Royal Astronomical Society under the title A detached stellar-mass black hole candidate in the globular cluster NGC 3201. The study was led by Benjamin Giesers of the Georg-August-University of Göttingen and included members from Liverpool John Moores University, Queen Mary University of London, the Leiden Observatory, the Institute of Astrophysics and Space Sciences, ETH Zurich, and the Leibniz Institute for Astrophysics Potsdam (AIP).

    See the full article here .

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  • richardmitnick 8:43 am on January 20, 2018 Permalink | Reply
    Tags: , , , , Researchers Develop a New Low Cost/Low Weight Method of Searching for Life on Mars, Universe Today   

    From Universe Today: “Researchers Develop a New Low Cost/Low Weight Method of Searching for Life on Mars” 

    universe-today

    Universe Today

    19 Jan , 2018
    Evan Gough

    1
    Study co-author I. Altshuler sampling permafrost terrain near the McGill Arctic research station, Canadian high Arctic. Image: Dr. Jacqueline Goordial

    Researchers at Canada’s McGill University have shown for the first time how existing technology could be used to directly detect life on Mars and other planets. The team conducted tests in Canada’s high arctic, which is a close analog to Martian conditions. They showed how low-weight, low-cost, low-energy instruments could detect and sequence alien micro-organisms. They presented their results in the journal Frontiers in Microbiology.

    Getting samples back to a lab to test is a time consuming process here on Earth. Add in the difficulty of returning samples from Mars, or from Ganymede or other worlds in our Solar System, and the search for life looks like a daunting task. But the search for life elsewhere in our Solar System is a major goal of today’s space science. The team at McGill wanted to show that, conceptually at least, samples could be tested, sequenced, and grown in-situ at Mars or other locations. And it looks like they’ve succeeded.

    See the full article here .

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  • richardmitnick 10:48 am on January 10, 2018 Permalink | Reply
    Tags: , , , , The Night Sky Magic of the Atacama, Universe Today   

    From Universe Today: “The Night Sky Magic of the Atacama” 

    universe-today

    Universe Today

    10 Jan , 2018
    Paul M. Sutter

    1
    The ESO’s Paranal Observatory sits proudly above the Atacama desert. No image credit.

    There’s nothing an astronomer – whether professional or amateur – loves more than a clear dark night sky away from the city lights. Outside the glare and glow and cloud cover that most of us experience every day, the night sky comes alive with a life of its own.

    Thousands upon countless thousands of glittering jewels – each individual star a pinprick of light set against the velvet-smooth blackness of the deeper void. The arching band of the Milky Way, itself host to billions more stars so far away that we can only see their combined light from our vantage point. The familiar constellations, proudly showing their true character, drawing the eye and the mind to the ancient tales spun about them.

    There are few places left in the world to see the sky as our ancestors did; to gaze in wonder at the celestial dome and feel the weight of billions of years of cosmic history hanging above us. Thankfully the International Dark Sky Association is working to preserve what’s left of the true night sky, and they’ve rightfully marked northern Chile to preserve for posterity.

    There, the Elqui Valley and the Atacama Desert host night skies impossible to see elsewhere. Away from cities, tucked between the Pacific coast and the high peaks of the Andes, the dry desert air and high elevations make for some of the best observing grounds you can find on Earth.

    See the full article here .

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  • richardmitnick 12:42 pm on December 23, 2017 Permalink | Reply
    Tags: , , , , Universe Today, What is the Radial Velocity Method?   

    From Universe Today: “What is the Radial Velocity Method?” 

    universe-today

    Universe Today

    22 Dec , 2017
    Matt Williams

    1
    Artist’s impression of Proxima b, which was discovered using the Radial Velocity method. Credit: ESO/M. Kornmesser

    The hunt for extra-solar planets sure has heated up in the past decade or so! Thanks to improvements made in instrumentation and methodology, the number of exoplanets discovered (as of December 1st, 2017) has reached 3,710 planets in 2,780 star systems, with 621 system boasting multiple planets. Unfortunately, due to the limits astronomers are forced to contend with, the vast majority have been discovered using indirect methods.

    When it comes to these indirect methods, one of the most popular and effective is the Radial Velocity Method – also known as Doppler Spectroscopy. This method relies on observing the spectra stars for signs of “wobble”, where the star is found to be moving towards and away from Earth. This movement is caused by the presence of planets, which exert a gravitational influence on their respective sun.

    Description:

    Essentially, the Radial Velocity Method consists not of looking for signs of planets themselves, but in observing a star for signs of movement. This is deduced by using a spectometer to measure the way in which the star’s spectral lines are displaced due to the Doppler Effect – i.e. how light from the star is shifted towards the red or blue end of the spectrum (redshift/blueshift).

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    Diagram detailing the Radial Velocity (aka. Doppler Shift) method. Credit: Las Cumbres Observatory.

    These shifts are indications that the star is moving away from (redshift) or towards (blueshift) Earth. Based on the star’s velocity, astronomers can determine the presence of a planet or system of planets. The speed at which a star moves around its center of mass, which is much smaller than that of a planet, is nevertheless measurable using today’s spectrometers.

    Until 2012, this method was the most effective means of detecting exoplanets, but has since come to be replaced by the Transit Photometry.

    Planet transit. NASA/Ames

    Nevertheless, it remains a highly effective method and is often relied upon in conjunction with the Transit Method to confirm the existence of exoplanets and place constraints on their size and mass.

    See the full article here .

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