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The first ever image of a black hole

First Image of a Black Hole

The first ever image of a black hole
The first ever image of a black hole, created using the Event Horizon Telescope, showing the black hole’s dark silhouette at the centre of its luminous accretion disk. Credit: Event Horizon Telescope Collaboration – Click to enlarge

A global network of radio telescopes known as the Event Horizon Telescope  (EHT) has produced the first ever image of the silhouette of a black hole.

The image shows hot luminous gas surrounding the black hole’s event horizon – the sphere beyond which light cannot escape the black hole’s gravitational influence.

The team responsible has worked for over a decade to improve upon the technique of Very Long Baseline Interferometry in order to capture the image. The resolution of a telescope is usually dependent upon the size of the dish, or aperture – usually equivalent to the width of the mirror or lens in an optical telescope or the the width of the dish in the case of a radio telescope. The technique of interferometry creates a much larger ‘synthetic aperture’ by linking the images from two or more telescopes together. The further apart the telescopes, the larger the synthetic aperture. The EHT’s synthetic aperture has a resolution equivalent to a dish with a diameter equal to the distance between Spain and the South Pole – where the two furthest apart telescopes in the array are located.

Five petabytes of data were used to construct the image. Because current internet speeds are not sufficient to handle this amount of data, it had to be physically transported to a central location from all eight sites in the EHT array.

Image of luminous gas at the core of the M87 galaxy, marked with the position of the black hole and its accretion disk
A close-up of the core of the M87 galaxy, from the Chandra X-ray Observatory. Image credit: NASA/CXC/Villanova University/J. Neilsen – Click to enlarge

The black hole is located at the center of the M87 galaxy – a supergiant elliptical galaxy in the constellation of Virgo. Estimates for the mass of this black hole range from around 3.5 to 6.6 billion times the mass of the Sun.

The supermassive black hole is surrounded by a rotating accretion disk of ionized gas. The disk rotates at a velocity of roughly 1,000 km per second and has a maximum radius of around 0.2 light years, or around 12,000 Astronomical Units (where 1 Astronomical Unit (AU) is the equivalent to the average distance between the Earth and the Sun). The radius of the black hole’s event horizon – or Schwarzschild radius – is around 120 AU.

The black hole’s powerful magnetic field causes it to emit a narrow jet of ionised material from the accretion disk aligned with its axis of rotation. The material in this jet travels at relativistic speeds and reaches a distance of at least 5,000 light years from the black hole.

M87's relativistic jet
Hubble Space Telescope image showing the jet of subatomic particles streaming from the black hole at the center of the M87 galaxy. Credits: NASA and the Hubble Heritage Team (STScI/AURA) – Click to enlarge.

water-ice cliff on Mars

Cliffs of Ice Found on Mars

water-ice cliff on Mars
Enhanced-colour image, showing a water-ice cliff, or scarp, on Mars, taken with the High Resolution Imaging Science Experiment (HiRISE) camera on NASA’s Mars Reconnaissance Orbiter. The exposed ice is shown in blue dropping about 80 metres from the level ground in the upper third of the image. (Credits: NASA/JPL-Caltech/UA/USGS) – click to enlarge
Water ice deposits have been found in cliff-like structures known as ‘scarps’ at eight different sites on Mars, using the HiRISE camera on NASA’s Mars Reconnaissance Orbiter.

It has previously been shown that there is shallow ground ice under roughly a third of the Martian surface, detected with spectrometers and ground-penetrating radar from orbiting spacecraft. The exposed faces of these scarps provide us with a cross-sectional view though this ice, which is over 100 metres thick in some places. Continue reading

Oumuamua Trajectory

Interstellar Object Discovered in Our Own Solar System

Oumuamua Trajectory
The trajectory of Oumuamua 1I/2017 U1 through our Solar System (credit: NASA/JPL-Caltech) – click to enlarge

On 19 October 2017, an astronomer at the Haleakala Observatory, Hawaii, spotted an object passing through our solar system on an unusual hyperbolic trajectory. The strange cigar-like shape of the object lead some to speculate that it could be the product of an extraterrestrial civilization. Continue reading

Spitzer TRAPPIST-1 planet observations

Seven Earth-Like Planets Found Orbiting TRAPPIST-1

On 22 February 2017, astronomers announced that the faint Jupiter-sized ultra-cool red dwarf star TRAPPIST-1, in the constellation of Aquarius, is host to seven Earth-sized planets, all of which are within the stars’ ‘habitable zone’, where it is possible that liquid water could be present.

The exoplanets have not yet been imaged directly but were detectable due to the dimming of the light from TRAPPIST-1, as the planets transited across the face of the star.
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Gravitational Waves Detected

The first ever confirmed detection of gravitational waves has been announced by the Laser Interferometer Gravitational-wave Observatory (LIGO) at a press conference held in Washington DC at 10:30 EST on Thurday, 11 February 2016 .

LIGO’s detection of ripples in the fabric of spacetime has been heralded as one of the scientific breakthroughs of the century and promises to mark the  dawn of a new science of gravitational-wave astronomy.
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