Showing posts with label astronomy. Show all posts
Showing posts with label astronomy. Show all posts
Sunday, August 6, 2023
Friday, June 30, 2023
Gravitational waves create a 'cosmic symphony' that scientists are tuning into - National Science Foundation
Based on his Theory of General Relativity,in 1915 Albert Einstein predicted the existence of gravitational waves,which are ripples in spacetime caused by massive cosmic events.Their existence wasn't verified until 2016 by the Laser Interferometer Gravitational-Wave Observatory (LIGO).Additionally,a network of two radio telescopes at Arecibo,Puerto Rico and Green Bank,West Virginia monitoring pulsars,which are highly magnetized,rapidly rotating neutron stars,were successfully enlisted in the search for gravitational waves.It is the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) sponsored by the National Science Foundation,and reported the first results of the project in 2023,the detection of background gravitational waves based on more than 15 years of radio telescope data.
Sunday, July 17, 2022
Monday, August 21, 2017
Solar Eclipse 2017 - inside the science of the rare event
Scientists are able to observe layers of the Sun's atmosphere during a solar eclipse that they cannot image otherwise.The corona,the outermost layer of the Sun,is a halo of gas streaming out from the Sun's surface in plumes and loops.Eclipse observing will help to solve the question of why the corona is hotter than the Sun's surface.Remember that it is cooler the farther away you get from a stove;that is not the case with the Sun,where the opposite is occurring.The photosphere surface of the Sun that emits sunlight is an average of 5500 degrees Centigrade;but the corona above it is up to millions of degrees C.Studying the corona during an eclipse and measuring how quickly the coronal gas oscillates can help distinguish between the general classes of ideas about this problem or perhaps ascertain that both processes are occurring:
1.The nanoflame hypothesis is a model that suggests that millions of tiny explosions could combine to heat up the corona.Millions of the flares going off per second ,each with a billionth as much energy as a large flare,would keep the corona broiling hot.
2.Magnetic or Alfven waves propagate through coronal loops,interacting with one another and dissipating some of their energy,either in the lower ends of the loop or throughout the corona.*
Rapid readouts with Charge-Coupled Devices,or CCDs,on ground-based telescopes will capture images several times per second-much faster than space telescopes can.*
NASA is funding 11 proposals:six for coronal studies and five for the response of Earth's atmosphere to dramatic eclipse cooling.A variety of observations from ground and space will provide the most comprehensive study ever made of the infrared corona,its spectrum and its polarisation.*
Combining ground-based observations with those from satellites in the visible,UV,X-ray and radio parts of the spectrum will provide the most complete view of the solar atmosphere ever obtained.*
A small group of scientists will use the small pixels and precise calibration of CCD detectors to test Einstein's theory of relativity by looking for evidence that the Sun's mass is bending the light of distant stars behind it,an effect caused by the relativistic warping of space-time.
First,the telescopes will be calibrated by measuring several nighttime star images.Because of the ESA's newly-released catalog of star positions,we know their positions with very high precision,so we can look for any deflections caused by the Sun more easily,with fewer calibrations of the telescopes.
1.The nanoflame hypothesis is a model that suggests that millions of tiny explosions could combine to heat up the corona.Millions of the flares going off per second ,each with a billionth as much energy as a large flare,would keep the corona broiling hot.
2.Magnetic or Alfven waves propagate through coronal loops,interacting with one another and dissipating some of their energy,either in the lower ends of the loop or throughout the corona.*
Rapid readouts with Charge-Coupled Devices,or CCDs,on ground-based telescopes will capture images several times per second-much faster than space telescopes can.*
NASA is funding 11 proposals:six for coronal studies and five for the response of Earth's atmosphere to dramatic eclipse cooling.A variety of observations from ground and space will provide the most comprehensive study ever made of the infrared corona,its spectrum and its polarisation.*
Combining ground-based observations with those from satellites in the visible,UV,X-ray and radio parts of the spectrum will provide the most complete view of the solar atmosphere ever obtained.*
A small group of scientists will use the small pixels and precise calibration of CCD detectors to test Einstein's theory of relativity by looking for evidence that the Sun's mass is bending the light of distant stars behind it,an effect caused by the relativistic warping of space-time.
First,the telescopes will be calibrated by measuring several nighttime star images.Because of the ESA's newly-released catalog of star positions,we know their positions with very high precision,so we can look for any deflections caused by the Sun more easily,with fewer calibrations of the telescopes.
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