Category: Space

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An orange ring in the blackness of space

How cool is it that we now have an actual image of the event horizon of a black hole! More precisely: it’s the glowing accretion disc of matter falling into the black hole, and the event horizon’s silhouette.

The Event Horizon Telescope, actually a worldwide array of telescopes, used interferometry to effectively create a planet-sized telescope to see the light around the supermassive black hole at the center of M87, a galaxy 55 million light years away.

I remember talking with a college classmate about giant interferometry telescopes back in the late 1990s. It’s incredible to see the technique actually making discoveries like this!

What we’re seeing in this image isn’t a top-down view of the accretion disc, but an angled one — think of Saturn’s rings — and the gravity of the black hole is bending the light from the disc. Phil Plait has a great article on the science behind the image. Katie Mack has a Twitter thread on how the image was produced, why the ring looks the way it does (it tells us which direction the disc is spinning!), plus simulations of this type of black hole seen from different viewing angles.

Here’s a paper talking about the history of black hole images, with a detailed discussion of what you should expect for the “shadow” image we’ve just seen. Check Fig 12, with renderings of shadows for disks at different angles arxiv.org

4x4 grid of black circles with red/yellow outlines, with bright and dark spots in the outlines.

— Katie Mack (@AstroKatie) April 10, 2019

Direct links to the articles she mentions:

And this Mastodon thread by @SohKamYung@mstdn.io collects some more articles worth checking out:

Forbes makes the excellent point that, while we’d seen a lot of circumstantial evidence for black holes over the last few decades, this confirms that they exist.

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Full moon, mostly red except for a whiter edge at the upper left.

The evening was hectic, and I almost forgot. I had literally just put my son to bed when I remembered, “The eclipse!” We went out to see if the sky was clear.

Clouds were rushing across the sky, but for the most part, it was clear, and we had a perfect view of the moon looking like a dark brown chunk of rock in the sky.

Update: It wasn’t quite this red to the eye, it was more of a deep brown, maybe slightly brick red. Probably a matter of retina sensitivity vs. camera sensors.

(Then I spent 10 minutes fighting with camera settings while he went back to bed.)

Update: I went back out about an hour later to check out the view as the moon left the earth’s shadow, and caught these two photos, taken about the same time with different exposures so that you can see either the lit portion of the moon, or the part that’s still in the earth’s shadow.

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I woke up way too early to see if the Super Blue Blood Moon* eclipse would be visible or blocked by clouds. (You never know, and I didn’t want to wake up the kiddo in the middle of a school night if there wasn’t anything to see.) I had a clear view, but the street lights were too bright to see the red color. It just looked dull brown.

So I took a couple of pictures, then went back in to wake up the kid. He still wanted to go out and see, but only for one look. Totally understandable. I carried him out, we looked at the darkened moon, then I carried him back in and put him back to bed.

It’s the third lunar eclipse he’s seen, though one of them we didn’t get to see much of since it was so cloudy. And while it’s not as cool as a total solar eclipse, it’s something you can see with no special equipment by walking out into your front yard anywhere in the world that has a view of the moon during the several hours it takes the Earth’s shadow to move across it.

I went back out one last time to try for some photos of totality, but they didn’t come out any better than the ones I took the first time. I looked around for a spot that might be darker and still have a view of the moon (without trespassing in someone else’s back yard), but didn’t see one — there are way too many lights at night these days. Then I tried to place the constellations I could see, and failed. Then I went back in to go back to bed.

Unfortunately I don’t think I really got back to sleep, so I’ve been dragging all morning. The interruption didn’t help the kiddo either, so getting him to school was a bit of a challenge.

*Blood moon: lunar eclipse, Earth’s shadow darkening the moon & turning it red. Cool to see, widely visible.
Super moon: full moon during closest point in orbit, looks slightly bigger.
Blue moon: 2nd full moon in a calendar month, otherwise no difference.

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Night sky with *very* bright cloud trail on one side, and on the other, a small bright spot with two tails branching off like a boat's wake.

Yesterday’s Falcon 9 rocket launch from Vandenberg AFB, seen across Southern California.

I walked outside and saw a bright spot (presumably the rocket) moving across the sky, trailing an expanding shell of vapor.

I ran back inside shouting “come see this, fast!” and grabbed the better camera, but it wouldn’t focus, so I snapped the top photo with my phone.

The yellow light is a street lamp. The upper bright spot is the moon. I believe the lower left is the rocket, and the lower right is the booster stage. A ring of light pulsed outward from the booster stage at one point.

The vapor trail persisted for another 10 minutes after the rocket and booster were no longer visible, and it was high enough to continue reflecting sunlight, even though it was an hour past sunset.

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I’ve always wanted to see a total solar eclipse, but until now I never had the opportunity. I’ve caught a number of partial solar eclipses over the years, and quite a few lunar eclipses. This year’s “Great American Eclipse” was perfect: it passed close to Portland, where we have family, and we could visit friends on the way up.

By the time I reserved our hotel there was nothing left inside the path of totality, but we could still get an expensive room in Portland. I reserved that immediately for the nights before and after, then a motel for a few nights before so we would have time to visit, then we planned out the trip up and back.

Driving Into the Path

The morning of August 21, we got up at 5:30 to drive south into the path of the eclipse. We didn’t actually make it out the door until at least 6:30, and the parking attendant had lost our key (fortunately we had two, and they did eventually find it that afternoon), and then we got lost trying to find an ATM in case we had to pay a ton to park in someone’s field (one way streets and bridges and driving into the early morning sun), but we got on the road toward Salem by around 7:15/7:30, with our eclipse glasses, water, snacks/emergency food, and a very sleepy 6½ year old.

The threatened traffic jam carpocalypse didn’t materialize. There were slowdowns, sure, but nothing we hadn’t experienced on the way out of LA. Our nav system (which J. calls the “map lady”) sent us onto a side road at one point, and we drove through the countryside a while before getting back onto the interstate.

Continue reading →

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Went with the family to see Space Shuttle Endeavour and a Pixar-themed exhibit on computer animation at the California Science Center.

The 6YO loved the Pixar exhibit, which broke down all the steps to creating a computer-animated movie into separate hands-on centers where you could do things like…

  • Apply different textures and bump maps to an object.
  • Rig a character for movement.
  • Change the lighting of a scene (real or virtual).
  • Define a shape in a 3D grid and watching the computer rotate it (way too much time on this one).
  • Create your own stop-motion animation by moving an actual desk lamp.

The only way we got him out was to point out that the museum was closing, and we only had 10 minutes left to get to the touch pools he’d said he wanted to visit. As it turned out, the pools shut down about two minutes before we got there, but staff was willing to let him look at the starfish. And we did catch the last desert flash flood simulation of the day.

As for the shuttle…he wasn’t impressed. He insisted on taking the simulator ride, but the real thing? I guess it’s old news when the whole fleet’s already been shut down by the time you start hanging onto long-term memories. 🤷

Admittedly, a big aluminum hut isn’t as suitable a viewing area for Endeavour as open space in broad daylight, surrounded by an enthusiastic crowd. Though that might have been the fact that it was my first time getting up close. On the other hand, this time I could see both sides. Heck, I could walk under it!

There is a new building in the works, where they’ll be displaying it with one of the external tanks in launch position. I’m sure it will lead to plenty of cartoons and movies where someone goes to the museum, breaks into the shuttle and blasts off.

I couldn’t make the building line up with my memories of visits when I was younger, back when it was the Museum of Science and Industry. The only thing I could match up at all were the wall facing the Exposition Park rose garden, and some of the buildings by the parking lot (a sunken structure now, but I remember it being flat).

Then again, what I remember are specific exhibits more than the layout: a big math/physics exhibit, a chicken incubator, and a multi-screen cartoon about energy sources and engine types called “The Water Engine.” (Each screen has a character talking up internal combustion, flywheels, mag-lev, electric, etc. I still quote the Peter Lorre-inspired fuel-cell scientist saying “And then…we burn the hydrogen!”)

It turns out there’s a good reason nothing fit my memory: They tore down the whole building in the late 1990s, preserving only that one wall!

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Clouds and timing squashed the “supermoon” and “blood moon” effects here, but it was still the most unusual lunar eclipse I’ve experienced.

Usually I’ll stay up late or get up early and go outside to watch the eclipse by myself. Last year I took my then-three-year-old son out to watch an eclipse around midnight.

Tonight’s eclipse got underway before local moonrise, and I wanted to see it as soon as possible. So J. (now four and a half) and I went out to an intersection in a residential neighborhood near the top of a hill with a clear view of the eastern horizon. We arrived at sunset, and two other people were looking eastward: a woman with a camera and full tripod, and a man with binoculars. The four of us all set up on a triangular traffic island on the northern side of the intersection.

Flat layers of clouds streaked the sky, and we worried that there might not be much to see at all, but it was only a few minutes before a slightly-off crescent moon rose due east of us, right in line with the street. Continue reading →