Starts With a Bang! 1 Aug 2019, 14:01 UTC The supermassive black hole at the center of the Milky Way is the most extreme astrophysical object located within a million light-years of Earth. With an estimated four million solar masses, it’s the largest black hole in our galaxy and second largest, behind Andromeda’s, in the entire Local Group. If your goal is to probe Einstein’s theory of General Relativity more stringently than ever before, the environment around this black hole is the best testing ground provided by nature. Since 1995, a team of astronomers led by Andrea Ghez at UCLA has been studying the orbits of stars near the galactic center. As time has progressed, their observational tools and techniques have improved. In 2018, the closest orbiting star to our supermassive black hole, S0–2, made its closest approach, reaching 2.7% the speed of light. In a tremendous new result, Einstein’s theory has been confirmed as never before. Here’s how.
Astronomy Now 1 Aug 2019, 13:33 UTC The four 1-metre SPECULOOS telescopes at the Paranal Observatory in Chile, designed to Search for habitable Planets EClipsing ULtra-COOL Stars, captured this spectacular view of Centaurus A (NGC 5128), a galaxy 11 million light years from Earth that harbours a 100-million-solar-mass black hole at its core. Discovered in 1826, it is the closest active galactic nucleus and a familiar target for professional and amateur astronomers alike. Researchers attribute the galaxy’s unusual appearance to a collision in the remote past between an elliptical galaxy and a smaller spiral. This image shows red and pink star-forming regions and clusters of young blue stars at top right. The vast dust clouds towards the centre of Centaurus A are slowly being consumed by the central black hole, resulting in powerful radio emissions.
The Planetary Society Blog 31 Jul 2019, 19:03 UTC Years of computer simulations. Countless ground tests. They've all led up to now. The Planetary Society's crowdfunded LightSail 2 spacecraft is successfully raising its orbit solely on the power of sunlight.
Universe Today 31 Jul 2019, 18:17 UTC The most comprehensive and widely-held theory of how the Moon formed is called the ‘giant impact hypothesis.’ That hypothesis shows that about 150 million years after the Solar System formed, a roughly Mars-sized planet named Theia collided with Earth. Though the timeline is hotly-debated in the scientific community, we know that this collision melted Theia and some of Earth, and that molten rock orbited around Earth until it coalesced into the Moon.
Starts With a Bang! 31 Jul 2019, 14:01 UTC When you hold out your palm and point it towards the sky, what is it that’s interacting with your hand? You might correctly surmise that there are ions, electrons and molecules all colliding with your hand, as the atmosphere is simply unavoidable here on Earth. You might also remember that photons, or particles of light, must be striking you, too. But there’s something more striking your hand that, without relativity, simply wouldn’t be possible. Every second, approximately one muon — the unstable, heavy cousin of the electron — passes through your outstretched palm. These muons are made in the upper atmosphere, created by cosmic rays. With a mean lifetime of 2.2 microseconds, you might think the ~100+ km journey to your hand would be impossible. Yet relativity makes it so, and the palm of your hand can prove it. Here’s how.
Physics World Blog 31 Jul 2019, 11:30 UTC When we look up at the Moon from our Earthly vantage point, we see a familiar face of shadowed craters and bright ridges. But nowadays, with the aid of satellites and telescopes, we’re also able to look beyond that well-known visage and see our nearest neighbour in a different light. Sarah Tesh picks some of her favourite alternative views of the Moon.