Thursday Throughput for 4/11/19
[ThTh1] Black holes were first theorized in the 18th century by John Michell as objects with gravitational fields so strong that light can not escape from the surface. In the latter half of the 20th century, we began to detect black holes. Not directly but through their influence: either the effect of their gravity on the orbits of nearby of objects or the emissions of the hot bright disk of material spiraling into them (the accretion disk). Cygnus X-1 was the first black hole detected this way. Observations showed that a blue supergiant was orbiting a massive object that was invisible in the optical but giving off copious X-rays. But even as our technology has advanced, we’ve never been able to see a black hole because they are extremely compact.
The image below is the closest we will ever get to actually “seeing” a black hole. What you’re seeing is an image created by eight radio telescopes spread out across the world from the South Pole to Greenland comprising the Event Horizon Telescope. They use a process called interferometry to combine the signals of the telescopes so that they resolve details as if they were a telescope as vast as the separation between them. In this case, they can resolve details down to a precision of 20 micro-arcseconds (enough to read a newspaper in New York from a sidewalk café in Paris, as the press release notes). For comparison, your eye can resolve details down to about one arc-minute, if you have your glasses on. The orange material in the image is the accretion disk. The dark hole at the center is the black hole, which is a few times as big as our solar system but weighs 6.5 billion times as much as the Sun.
The accretion disk is not actually orange. That’s false color for an image that comes from the radio. If you were to see this with your eye, it would probably be white (you can read more about how these image are created here). What’s more, the image is still blurry. Finer resolution could make it look more like the simulated image which shows a thin band of material swirling into oblivion. Here’s a video showing the context of what you’re seeing.
Event Horizon has also imaged the black hole at the center of our Galaxy — Sgr A*. That image may come out soon. The rumor is that the resolution is so good that we can actually see the accretion disk changing, making image processing tricky. Stay tuned!
[ThTh2] Earth has eclipses maybe every six months when the moon’s orbit aligns with the position of the Sun. Mars experiences them every day.
[ThTh3] Edwin Hubble. Scientist. Astronomer. Discoverer of the expansion of the Universe. Namesake of a great telescopes. Also, basketball player.
Tonight is the #NationalChampionship game! Did you know Edwin Hubble was a gifted basketball player? He and his @UChicago team even won a conference title. His basketball flew in space with fellow alum John Grunsfeld (@SciAstro) on the telescope’s final servicing mission. pic.twitter.com/VYImUSmToa
— Hubble (@NASAHubble) April 8, 2019
PS -- Wahoowa! I went to UVa for grad school and was delighted at this year’s outcome, even though I didn’t pick them to win the OT Final Four competition.
[ThTh4] So apparently one of the most lethal spider venoms in the world may help stroke victims. That’s assuming this isn’t a PR campaign being run by the venomous spider itself.
[ThTh5] LIGO, the gravitational wave detector, has started its third run. And on Tuesday, it made its first detection of the new run: two black holes smashing together four billion years ago.
[ThTh6] One of the pictures you take when you first start astrophotography is to set up a camera for a long exposure and watch the stars trails through the sky as the Earth rotates. This video reverses that, fixing on the stars and watching the Earth rotate.
Stabilizing to the Milky Way shows the rotation of the Earth pic.twitter.com/C5YPZMEG7v
— Domenico Calia (@CaliaDomenico) April 9, 2019
[ThTh7] Bombs away!
[ThTh8] Usually when people talk about land whales, I assume they’re telling me I need to lose weight.
[ThT9] The entire field of planetary science is being upended on a seemingly weekly basis.
[ThTh10] This article is a couple of years old, but was RT’d into my feed this week. It disputes the notion that our brains are similar to computers, pointing out critical differences between the way we think and the way computers “think”. It’s right on the money, in my opinion. And I’m always happy to see someone taking on Kurtzweil’s ideas.