OrbitalHub

NASA dicit:

Scientists have discovered that a mysterious pressure dubbed “dark energy” makes up about 68 percent of the total energy content of the cosmos, but so far we don’t know much more about it. Exploring the nature of dark energy is one of the primary reasons NASA is building the Wide Field Infrared Survey Telescope (WFIRST), a space telescope whose measurements will help illuminate the dark energy puzzle. With a better understanding of dark energy, we will have a better sense of the past and future evolution of the universe.

Astronomers have measured the rate of of the universe’s expansion by using ground-based telescopes to study relatively nearby supernova explosions. The mystery escalated in 1998 when Hubble Space Telescope observations of more distant supernovae helped show that the universe actually expanded more slowly in the past than it does today. The expansion of the universe is not slowing down due to gravity, as everyone thought. It’s speeding up.

While we still don’t know what exactly is causing the acceleration, it has been given a name — dark energy. This mysterious pressure remained undiscovered for so long because it is so weak that gravity overpowers it on the scale of humans, planets and even the galaxy. It is only on an intergalactic scale that dark energy becomes noticeable, acting like a sort of weak opposition to gravity.

What exactly is dark energy? More is unknown than known, but theorists are chasing down a couple of possible explanations. Cosmic acceleration could be caused by a new energy component, which would require some adjustments to Einstein’s theory of gravity — perhaps the cosmological constant, which Einstein called his biggest blunder, is real after all.

Alternatively, Einstein’s theory of gravity may break down on cosmological scales. If this is the case, the theory will need to be replaced with a new one that incorporates the cosmic acceleration we have observed. Theorists still don’t know what the correct explanation is, but WFIRST will help us find out.

Discovering how dark energy has affected the universe’s expansion in the past will shed some light on how it will influence the expansion in the future. If it continues to accelerate the universe’s expansion, we may be destined to experience a “Big Rip.” In this scenario, dark energy would eventually become dominant over the fundamental forces, causing everything that is currently bound together — galaxies, planets, people — to break apart. Exploring dark energy will allow us to investigate, and possibly even foresee, the universe’s fate. Watch this video to learn more about dark energy and how WFIRST will study it.

Video Credit: NASA’s Goddard Space Flight Center/Scott Wiessinger (USRA): Lead Producer/Krystofer Kim (USRA): Lead Animator/Chris Smith (USRA): Animator/Sophia Roberts (AIMM): Narrator/Francis Reddy (University of Maryland College Park): Lead Science Writer/Claire Andreoli (NASA/GSFC): Lead Public Affairs Office

NASA dicit:

Tour the GJ 357 system, located 31 light-years away in the constellation Hydra. Astronomers confirming a planet candidate identified by NASA’s Transiting Exoplanet Survey Satellite subsequently found two additional worlds orbiting the star. The outermost planet, GJ 357 d, is especially intriguing to scientists because it receives as much energy from its star as Mars does from the Sun.

Credit: NASA’s Goddard Space Flight Center/Chris Smith (USRA): Lead Producer/Chris Smith (USRA): Lead Animator/Francis Reddy (University of Maryland College Park): Lead Science Writer

NASA dicit:

In order to know how the universe will end, we must know what has happened to it so far. This is just one mystery NASA’s forthcoming Wide Field Infrared Survey Telescope (WFIRST) mission will tackle as it explores the distant cosmos. The spacecraft’s giant camera, the Wide Field Instrument (WFI), will be fundamental to this exploration.

The WFI has just passed its preliminary design review, an important milestone for the mission. It means the WFI successfully met the design, schedule and budget requirements to advance to the next phase of development, where the team will begin detailed design and fabrication of the flight hardware.

WFIRST is a next-generation space telescope that will survey the infrared universe from beyond the orbit of the Moon. Its two instruments are a technology demonstration called a coronagraph, and the WFI. The WFI features the same angular resolution as Hubble but with 100 times the field of view. Data it gathers will enable scientists to discover new and uniquely detailed information about planetary systems around other stars. The WFI will also map how matter is structured and distributed throughout the cosmos, which should ultimately allow scientists to discover the fate of the universe.

The WFI is designed to detect faint infrared light from across the universe. Infrared light is observed at wavelengths longer than the human eye can detect. The expansion of the universe stretches light emitted by distant galaxies, causing visible or ultraviolet light to appear as infrared by the time it reaches us. Such distant galaxies are difficult to observe from the ground because Earth’s atmosphere blocks some infrared wavelengths, and the upper atmosphere glows brightly enough to overwhelm light from these distant galaxies. By going into space and using a Hubble-size telescope, the WFI will be sensitive enough to detect infrared light from farther than any previous telescope. This will help scientists capture a new view of the universe that could help solve some of its biggest mysteries, one of which is how the universe became the way it is now.

The WFI will allow scientists to peer very far back in time. Seeing the universe in its early stages will help scientists unravel how it expanded throughout its history. This will illuminate how the cosmos developed to its present condition, enabling scientists to predict how it will continue to evolve.

With its large field of view, the WFI will provide a wealth of information in each image it takes. This will dramatically reduce the amount of time needed to gather data, allowing scientists to conduct research that would otherwise be impractical.

With the successful completion of the WFI’s preliminary design review, the WFIRST mission is on target for its planned launch in the mid-2020s. Scientists will soon be able to explore some of the biggest mysteries in the cosmos thanks to the WFI’s wide field of view and precision optics.

Video Credit: NASA’s Goddard Space Flight Center/Scott Wiessinger (USRA)/Claire Saravia/Krystofer Kim (USRA)/Ashley Balzer

NASA dicit:

In the mid-1800s, mariners sailing the southern seas navigated at night by a brilliant star in the constellation Carina. The star, named Eta Carinae, was the second brightest star in the sky for more than a decade. Those mariners could hardly have imagined that by the mid-1860s the brilliant orb would no longer be visible. Eta Carinae was enveloped by a cloud of dust ejected during a violent outburst named “The Great Eruption.”

Because of Eta Carinae’s violent history, astronomers have kept watch over its activities. Although Hubble has monitored the volatile superstar for 25 years, it still is uncovering new revelations. Using Hubble to map the ultraviolet-light glow of magnesium embedded in warm gas, astronomers were surprised to discover the gas in places they had not seen it before.

Paul R. Morris (USRA): Lead Producer

Aaron E. Lepsch (ADNET): Technical Support

Video Credit: NASA’s Goddard Space Flight Center

NASA dicit:

Astronomers using NASA’s Fermi Gamma-ray Space Space Telescope and the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) have found a pulsar hurtling through space at nearly 2.5 million miles an hour — so fast it could travel the distance between Earth and the Moon in just 6 minutes.

Pulsars are superdense, rapidly spinning neutron stars left behind when a massive star explodes. This one, dubbed PSR J0002+6216 (J0002 for short), sports a radio-emitting tail pointing directly toward the expanding debris from a recent supernova explosion. Thanks to its narrow dart-like tail and a fortuitous viewing angle, astronomers can trace this pulsar straight back to its birthplace. Further study of J0002 will help us better understand how these explosions are able to ‘kick’ neutron stars to such high speed.

The pulsar is located about 6,500 light-years away in the constellation Cassiopeia. It was discovered in 2017 by a citizen-science project called Einstein@Home , which uses downtime on the computers of volunteers to process Fermi gamma-ray data and has identified 23 gamma-ray pulsars to date. J0002 spins 8.7 times a second, producing a pulse of gamma rays with each rotation, and has about 1.5 times the mass of the Sun. The pulsar lies about 53 light-years from the center of a supernova remnant called CTB 1. Its rapid motion through interstellar gas results in shock waves that produce the tail of magnetic energy and accelerated particles detected at radio wavelengths using the VLA. The tail extends 13 light-years and clearly points back to the center of CTB 1.

Using Fermi data and a technique called pulsar timing, the team was able to measure how quickly and in what direction the pulsar was moving across our line of sight thanks to Fermi’s 10-year data covering the entire sky. J0002 is speeding through space five times faster than the average pulsar and faster than 99 percent of those with measured speeds. It will eventually escape our galaxy.

Francis Reddy (University of Maryland College Park): Lead Science Writer

Scott Wiessinger (USRA): Lead Producer

Jeanette Kazmierczak (University of Maryland College Park): Science Writer

Music credit: “Forensic Scientist” from Killer Tracks

Video Credit: NASA Goddard

NASA dicit:

Astronomers have put together the largest and most comprehensive “history book” of galaxies into one single image, using 16 years’ worth of observations from NASA’s Hubble Space Telescope.

The deep-sky mosaic, created from nearly 7,500 individual exposures, provides a wide portrait of the distant universe, containing 265,000 galaxies that stretch back through 13.3 billion years of time to just 500 million years after the big bang. The faintest and farthest galaxies are just one ten-billionth the brightness of what the human eye can see. The universe’s evolutionary history is also chronicled in this one sweeping view. The portrait shows how galaxies change over time, building themselves up to become the giant galaxies seen in the nearby universe.

This ambitious endeavor, called the Hubble Legacy Field, also combines observations taken by several Hubble deep-field surveys, including the eXtreme Deep Field (XDF), the deepest view of the universe. The wavelength range stretches from ultraviolet to near-infrared light, capturing the key features of galaxy assembly over time.

Video Credit: NASA, ESA, G. Illingworth (University of California, Santa Cruz) and G. Bacon (STScI)