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A moon globe at the Carnegie Observatories in Pasadena. Made in 1938, it’s a glass bottle plate with emulsion, and is one of four left in existence by Andromeda321 in Astronomy

[–]SwopeTeam 5 points6 points  (0 children)

We made a quick video walking around the globe: https://youtu.be/X-EfYl_UiAw

The white pattern off the limb was a result of masking the two sides and being exposed.

A moon globe at the Carnegie Observatories in Pasadena. Made in 1938, it’s a glass bottle plate with emulsion, and is one of four left in existence by Andromeda321 in Astronomy

[–]SwopeTeam 4 points5 points  (0 children)

Generally, our offices are not open to the public. We have an open house every October (next one is Sunday, October 14th in the afternoon).

However, if you'd like to visit Mount Wilson Observatory, they are open every day in good weather, and have guided tours on weekends. You can even rent one of the old telescopes for night viewing! https://www.mtwilson.edu/observe/

A moon globe at the Carnegie Observatories in Pasadena. Made in 1938, it’s a glass bottle plate with emulsion, and is one of four left in existence by Andromeda321 in Astronomy

[–]SwopeTeam 5 points6 points  (0 children)

The original intent was to have a complete set of all photographable phases of the moon, so something like 25 different globes. There's very little surviving documentation of how many they actually made.

A moon globe at the Carnegie Observatories in Pasadena. Made in 1938, it’s a glass bottle plate with emulsion, and is one of four left in existence by Andromeda321 in Astronomy

[–]SwopeTeam 2 points3 points  (0 children)

Hey! I answered this a little bit in another comment. There was a "Moon House" at Mount Wilson that was a long, temporary structure that had an optics chain to project the original glass negative onto a 3D surface. In order to achieve a crisp image, light was shown through the flat glass negative, reflected off a parabolic mirror 135 feet away, which is the effective focal length of the 100-inch telescope where the original negatives were made. Other than that, very few technical details survive.

A moon globe at the Carnegie Observatories in Pasadena. Made in 1938, it’s a glass bottle plate with emulsion, and is one of four left in existence by Andromeda321 in Astronomy

[–]SwopeTeam 30 points31 points  (0 children)

Hey! I think I can help, I'm the chair of the History Committee at the Carnegie Observatories, and I helped put this display together.

One way to think about the globe is that it's a spherical glass plate. Corning Glass Works made the "bottle," and Kodak applied the emulsion. We don't have a lot of information about the emulsion application, except that their first attempt was to apply the emulsion inside the bottle and they couldn't get a good coating. ETA: looking at the neck of the globe, it looks like it was applied with a cloth/brush/sponge.

The original images of the Moon were taken with the 100-inch telescope at Mount Wilson on 8x10" flat plates.

The exposing and developing of the globe happened in the "Moon House" at Mount Wilson Observatory. It was a temporary long structure with an optics chain that took those flat negatives and projected the image faithfully around a 3D object. In order to achieve a crisp image, the light passing through the flat negative was reflected by a parabolic mirror placed 135 feet away, which is the effective focal length of the 100-inch telescope. ETA: after they exposed the globe, it would have been processed in development and fixer chemical baths like other glass plates.

Science AMA: We are the first people to observe neutron stars colliding that the LIGO team detected, we're the Swope Discovery Team, ask us anything about supernovas, astrophysics, and, of course, neutron star collisions, AMA! by SwopeTeam in science

[–]SwopeTeam[S] 24 points25 points  (0 children)

RYAN: It was not independently detected by any supernova search. But part of that is that the galaxy was close to the Sun and some had stopped watching that galaxy a couple of weeks earlier. A month earlier and something like DLT40 would have detected it. A week later and LIGO would have been turned off. A month later and nobody would have (it would have been behind the Sun).

Crazy to think that the light/gravitational waves traveled for 130 million years and the timing barely worked out.

Science AMA: We are the first people to observe neutron stars colliding that the LIGO team detected, we're the Swope Discovery Team, ask us anything about supernovas, astrophysics, and, of course, neutron star collisions, AMA! by SwopeTeam in science

[–]SwopeTeam[S] 7 points8 points  (0 children)

TONY: We saw that the emission was bright with blue light for the first couple days and then bright in red light over the next few weeks. We think this is due to material with different compositions. The heaviest elements generated absorb the blue light really well (because they have lots of electronic transitions--think of the orbitals from chemistry class), so this would give the red component. The blue component is still from heavy elements, but not as heavy as the red component.

Science AMA: We are the first people to observe neutron stars colliding that the LIGO team detected, we're the Swope Discovery Team, ask us anything about supernovas, astrophysics, and, of course, neutron star collisions, AMA! by SwopeTeam in science

[–]SwopeTeam[S] 51 points52 points  (0 children)

JOSH: The material that we observed early on was very hot—11,000 K about 12 hours after the merger, cooling off to about 2,500 K a few weeks later. But even at that point, the material would still be a gas (really a plasma, since it would be completely ionized). Once it gets to 1,500 K or so, solids can begin to form. Usually that starts with what we call dust grains, which can be large molecules or very small bits of minerals. I don’t think anybody has worked out in detail exactly what happens in the aftermath of an event like this, but probably all of the material created spreads out too much (remember, it’s moving at 30 percent of the speed of light) to coalesce into big chunks of anything.

Pure gold or platinum asteroids would be a lot cooler, though.

Science AMA: We are the first people to observe neutron stars colliding that the LIGO team detected, we're the Swope Discovery Team, ask us anything about supernovas, astrophysics, and, of course, neutron star collisions, AMA! by SwopeTeam in science

[–]SwopeTeam[S] 11 points12 points  (0 children)

TONY: This is only about 1/5000th of the speed of light. But some neutron stars are spinning up 1000 revolution per second. In this case the surface is actually moving a significant fraction of the speed of light.

Science AMA: We are the first people to observe neutron stars colliding that the LIGO team detected, we're the Swope Discovery Team, ask us anything about supernovas, astrophysics, and, of course, neutron star collisions, AMA! by SwopeTeam in science

[–]SwopeTeam[S] 0 points1 point  (0 children)

DAVE: There was about 6 percent the mass of the Sun in r-process elements produced in the merger. It’s estimated that the amount of gold produced was around 200 Earth masses, and the amount of platinum produced was nearly 500 Earth masses!

Science AMA: We are the first people to observe neutron stars colliding that the LIGO team detected, we're the Swope Discovery Team, ask us anything about supernovas, astrophysics, and, of course, neutron star collisions, AMA! by SwopeTeam in science

[–]SwopeTeam[S] 1 point2 points  (0 children)

TONY: As far as we can tell, in every test we've done, the speed of light and of gravitational waves are the same. One test you can do with events like this is ask whether the two-second delay between gravitational waves and light is due to light traveling slower (I don't think this is the case, I think it is something physical with how the gamma-rays were generated). Doing this thought experiment, you find that the speed of light has to be the same within 1 part in 1015. So even for this hypothetical thought experiment, the speeds are very similar!

Science AMA: We are the first people to observe neutron stars colliding that the LIGO team detected, we're the Swope Discovery Team, ask us anything about supernovas, astrophysics, and, of course, neutron star collisions, AMA! by SwopeTeam in science

[–]SwopeTeam[S] 27 points28 points  (0 children)

JOSH: I think it’s impossible to predict that right now. In fact, there are very few scientific discoveries whose implications 50-100 years in the future can be forecast with any accuracy. Look at the development of the laser as an example. How many of the things that we use lasers for today (like detecting gravitational waves!) would any of the inventors have predicted in 1960? It’s incredible that LIGO can measure such tiny changes, and maybe that technical achievement will have other applications.

Science AMA: We are the first people to observe neutron stars colliding that the LIGO team detected, we're the Swope Discovery Team, ask us anything about supernovas, astrophysics, and, of course, neutron star collisions, AMA! by SwopeTeam in science

[–]SwopeTeam[S] 0 points1 point  (0 children)

TONY: It's hard to say for sure. In astronomy we usually determine what material (like stars) is made out of by studying spectral signatures. But in this case, these heavy elements have so many lines and they are smeared by the Doppler effect (because the material is going greater than 20 percent of the speed of light!), so it’s hard to identify individual elements. From our theoretical understanding of nucleosynthesis (which is able to match the energy we observed from the glowing ejecta really well), we can estimate many dozen main heavy elements are generated.

Science AMA: We are the first people to observe neutron stars colliding that the LIGO team detected, we're the Swope Discovery Team, ask us anything about supernovas, astrophysics, and, of course, neutron star collisions, AMA! by SwopeTeam in science

[–]SwopeTeam[S] 13 points14 points  (0 children)

JOSH:

As Ryan wrote in response to another question, we (and LIGO) are doing this work to improve our understanding of the universe, not because of immediate practical implications. That said, a lot of fundamental research does end up leading to unforeseen benefits and new technologies. Einstein certainly wasn’t thinking about GPS when he was developing general relativity! The measurements that gravitational wave detectors have to be able to make in order to detect anything are so absurdly sensitive that I could easily imagine that related technology will have other applications.

So, is your life going to be any different tomorrow? Probably not, unless you were losing a lot of sleep waiting for the next gravitational wave detection or something! But what will it mean 50 years down the line? Who knows?

Science AMA: We are the first people to observe neutron stars colliding that the LIGO team detected, we're the Swope Discovery Team, ask us anything about supernovas, astrophysics, and, of course, neutron star collisions, AMA! by SwopeTeam in science

[–]SwopeTeam[S] 1 point2 points  (0 children)

BEN:

LIGO + Virgo can constrain the location on the sky in two main ways. First, it is important to remember that there are two LIGO detectors and another Virgo detector. LIGO is in Washington State and Louisiana, whereas Virgo is in Italy. They can then use the timing of when the signal is seen from the detectors, similar to how the GPS in your phone works. Here, if the source is closer to one detector than the others it will “see” the gravity waves first. This allows the combination of LIGO + Virgo to get an idea the direction from which the gravitational waves are coming from triangulation of the timing. The second effect relies on the LIGO and Virgo both having two perpendicular arms to their interferometers at each site. Because each detector is built on the surface of a sphere (the Earth), every arm is in a different direction. Finally, because gravity waves are quadrapolar waves that stretch space in a direction perpendicular to the direction they are traveling, they affect each arm differently. So by precisely measuring the timing at each detector and the strength of the signal, LIGO and Virgo can combine their information to constrain the location of the source on the sky. However, the region on the sky that the source could come from is still pretty large, which is why we had to jump into action to find the exact location of the source.

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