Mars’ nightside atmosphere glows and pulsates in this data animation from MAVEN spacecraft observations. Green-to-white false color shows the enhanced brightenings on Mars’ ultraviolet “nightglow” measured by MAVEN’s Imaging UltraViolet Spectrograph at about 70 kilometers (approximately 40 miles) altitude. A simulated view of the Mars globe is added digitally for context, with ice caps visible at the poles. Three nightglow brightenings occur over one Mars rotation, the first much brighter than the other two. All three brightenings occur shortly after sunset, appearing on the left of this view of the night side of the planet. The pulsations are caused by downwards winds which enhance the chemical reaction creating nitric oxide which causes the glow. Months of data were averaged to identify these patterns, indicating they repeat nightly.
Video credit: NASA/MAVEN/Goddard Space Flight Center/CU/LASP
NASA’s Lucy mission is launching in 2021 and will fly by seven different Trojan asteroids that are orbiting the same distance from the Sun as Jupiter. This video highlights the four main science objectives and the instruments aboard the spacecraft that will be utilized. Lucy will be the first space mission to study the Trojan asteroids, which are remnants of our early solar system.
Video credit: NASA’s Goddard Space Flight Center/Produced & Edited by: David Ladd (USRA)/Animations by: David Ladd (USRA), Walt Feimer (KBRwyle), Jacquelyn DeMink (USRA), Michael Lentz (USRA), Jonathan North (USRA)/Music: “Feels Good” – Wally Gagel & Xandy Barry [ASCAP], provided by Universal Production Music
When amateur astronomer Gennady Borisov discovered an interstellar comet zipping through our solar system on Aug. 30, 2019, scientists promptly turned their telescopes toward it hoping to catch a glimpse of this rare and ephemeral event. After all, no one had ever set eyes on a confirmed comet from a foreign star system, and it was clear from its projected trajectory that the alien visitor, named 2I/Borisov, would soon disappear from the sky forever.
Before it dimmed from view, a team of international scientists led by Martin Cordiner and Stefanie Milam at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, probed it with the world’s most powerful radio telescope: the Atacama Large Millimeter/submillimeter Array (ALMA) in northern Chile. The comet was near its closest approach to Earth at about 180 million miles, or nearly 300 million kilometers, away.
When the scientists peeked inside the halo of gas that formed around the comet as it came closer to the Sun and its ices began to vaporize, they detected something peculiar: 2I/Borisov was releasing gas with a greater concentration of carbon monoxide (CO) than anyone had detected in any comet at a similar distance from the Sun (within less than 186 million miles, or 300 million kilometers). 2I/Borisov’s CO concentration was estimated to be between nine and 26 times higher than that of the average solar system comet.
Video credit: NASA’s Goddard Space Flight Center/James Tralie (ADNET): Lead Producer, Lead Editor, Narrator/Lonnie Shekhtman (ADNET): Lead Writer/Martin Cordiner (Catholic University of America): Scientist, Stefanie Milam (NASA/GSFC): Scientist/ Aaron E. Lepsch (ADNET): Technical Support
A black hole is a region of spacetime where gravity is so strong that nothing—no particles or even electromagnetic radiation such as light—can escape from it. The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole. The boundary of the region from which no escape is possible is called the event horizon. Although the event horizon has an enormous effect on the fate and circumstances of an object crossing it, according to general relativity it has no locally detectable features. In many ways, a black hole acts like an ideal black body, as it reflects no light. Moreover, quantum field theory in curved spacetime predicts that event horizons emit Hawking radiation, with the same spectrum as a black body of a temperature inversely proportional to its mass. This temperature is on the order of billionths of a kelvin for black holes of stellar mass, making it essentially impossible to observe.
Objects whose gravitational fields are too strong for light to escape were first considered in the 18th century by John Michell and Pierre-Simon Laplace. The first modern solution of general relativity that would characterize a black hole was found by Karl Schwarzschild in 1916, although its interpretation as a region of space from which nothing can escape was first published by David Finkelstein in 1958. Black holes were long considered a mathematical curiosity; it was not until the 1960s that theoretical work showed they were a generic prediction of general relativity. The discovery of neutron stars by Jocelyn Bell Burnell in 1967 sparked interest in gravitationally collapsed compact objects as a possible astrophysical reality.
Black holes of stellar mass are expected to form when very massive stars collapse at the end of their life cycle. After a black hole has formed, it can continue to grow by absorbing mass from its surroundings. By absorbing other stars and merging with other black holes, supermassive black holes of millions of solar masses (M☉) may form. There is consensus that supermassive black holes exist in the centers of most galaxies.
Hear the rapid beat of HD 31901, a Delta Scuti star in the southern constellation Lepus. The sound is the result of 55 pulsation patterns TESS observed over 27 days sped up by 54,000 times. Delta Scuti stars have long been known for their apparently random pulsations, but TESS data show that some, like HD 31901, have more orderly patterns.
Video credit: NASA’s Goddard Space Flight Center and Simon Murphy, University of Sydney
A near-Earth object (NEO) is any small Solar System body whose orbit brings it to proximity with Earth. By convention, a Solar System body is a NEO if its closest approach to the Sun (perihelion) is less than 1.3 astronomical units (AU). If a NEO’s orbit crosses the Earth’s, and the object is larger than 140 meters (460 ft) across, it is considered a potentially hazardous object (PHO). Most known PHOs and NEOs are asteroids, but a small fraction are comets.
There are over 20,000 known near-Earth asteroids (NEAs), over a hundred short-period near-Earth comets (NECs), and a number of solar-orbiting spacecraft and meteoroids large enough to be tracked in space before striking the Earth. It is now widely accepted that collisions in the past have had a significant role in shaping the geological and biological history of the Earth. NEOs have become of increased interest since the 1980s because of greater awareness of the potential danger. Asteroids as small as 20 m can damage the local environment and populations. Larger asteroids penetrate the atmosphere to the surface of the Earth, producing craters if they impact a continent or tsunamis if they impact sea. Asteroid impact avoidance by deflection is possible in principle, and methods of mitigation are being researched.
Two scales, the Torino scale and the more complex Palermo scale, rate a risk based on how probable the orbit calculations of an identified NEO make an Earth impact and on how bad the consequences of such an impact would be. Some NEOs have had temporarily positive Torino or Palermo scale ratings after their discovery, but as of March 2018, more precise calculations based on longer observation arcs led in all cases to a reduction of the rating to or below 0.
Since 1998, the United States, the European Union, and other nations are scanning the sky for NEOs in an effort called Spaceguard. The initial US Congress mandate to NASA was to catalog at least 90% of NEOs that are at least 1 kilometre (0.62 mi) in diameter, which could cause a global catastrophe,and had been met by 2011. In later years, the survey effort has been expanded to smaller objects which have the potential for large-scale, though not global, damage.
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