An asteroid will occult Betelgeuse on December 12th | Hacker News Reader

An asteroid will occult Betelgeuse on December 12th

universetoday.com

242 pointsbelter67 comments

There's another article I was reading last week about this

https://skyandtelescope.org/astronomy-news/asteroid-will-cov...

It's really stunning how much information can be gathered from such an event.

All this knowledge merely from our single planet by tiny variations of measurements in finely calibrated instruments as if you were able to map out the city of Paris confined to the observations from a single window.

Great article, I've always been impressed by this too. It's neat that it sounds like even amateurs with nothing but a regular DSLR can contribute to this as well.

> By precisely timing the duration of the occultation from many sites simultaneously, they can refine their knowledge of the size and shape of the asteroid.

> Betelgeuse is the 10th brightest star in our skies (+0.5 magnitude), so observers need only modest equipment to participate.

> the easiest way to capture the event is to use a simple DSLR camera on a tripod ... video frames must have a short (few-millisecond) exposure time ... Millisecond accuracy timing is crucial ... [an app] for timestamping occultation observations is called Occult Flash Tag (Android) or AstroFlashTimer (iPhone)

I can imagine it helps to normalize the various perturbations from atmospheric non uniformity which may be able to help the higher quality measurements decrease the noise.

> Occult Flash Tag (Android)

Sadly this seems abandoned and it seems to have been removed from the Play Store. It's also not on F-Droid, even though it does seems to have a Git repo on Github.

> All this knowledge merely from our single planet by tiny variations of measurements in finely calibrated instruments as if you were able to map out the city of Paris confined to the observations from a single window.

Indeed, but I like to wonder how much of it will turn out to be wrong when (if) we finally get to visit it in person.

I mean, do you really want to believe that everything about something as practically infinite as the UNIVERSE could be learned from just a single planet in a few hundred years?

Because that would be pretty boring. :)

Well as a physicist I think it's safe to say this, of course you can't know everything from a single solar system. Most of the stuff we see/measure is massive, and the smaller stuff like exoplanets is general.

What we are doing now is like squinting while looking around a busy city street. You can get a sense of the cars, the people, etc. but you can't tell me exactly what the sign across the street says or what the hours for street parking are for that spot across the street and down two cars.

And the real interesting thing to us as living beings is other living beings/organisms no matter how different. And no matter the quality of your telescope or detectors, you are never going to be able to resolve anything that far away nor with any degree of certainty. So from the limits of physics, we know we are going to eventually need to get down from our windowed apartment and start walking the streets of Paris. For no matter how long we stare, we will never truly know the smell of the bakery a few streets over until we walk through it's door.

And to those that say robotic missions are the only true way, they are missing out on the truly human and sentient reason to go. Through individual experience we can create more than just new knowledge, we can expand upon the human experience as well as create new art to share those experiences.

You know those pictures of a spiral galaxy that say "you are here?" pointing to the outer edge.

You actually aren't. That's not our galaxy, we don't have pictures like that of our actual galaxy and don't have any idea how to get one.

Also there's tons of other fundamental limits - galaxies that will likely forever be just faint pixels, the distribution of photons being too dispersed for any detector.

Also there's the light horizon problem - we can only see to what the age of the universe allows, not necessarily to its extent.

Beyond that let's say there's a 100% confidence of methane on a planet around one of the Alpha Centauri stars, say Proxima Centari B, a pretty solid indicator of life. Ok now what?

Probes like Voyager would take 75,000 years to get there. If we had loaded a ship with neanderthals during paleolithic times, their descendants would just be arriving now. Even the much touted solar sails would take 25 years to get there and 4 years to send back any data. If magically launched tomorrow, it'd be 2052 before first byte. The distance is really wildly insurmountable and that's just our next door neighbor.

If I could time travel say, 25,000 years hence and we somehow had not blown ourselves up, I could imagine even then asking "how much of space have you explored" and getting an answer like "well, the milky way is 100,000,000,000 stars and 100,000 light years across so about 0.001% of that." There's ballpark a trillion galaxies btw. At some point, the numbers become meaninglessly large, might as well just call it a zillion.

You know those signs with the city map with an arrow saying "you are here"? Most of those are drawings, not photographs. So what?

Just because we can't take a picture with a camera, shouldn't we build a model of something?

ceci n'est pas une pipe

I find it amazing what science can do nowadays. Makes you wonder where we're going to be in one hundred years from now!

This is actually a much better article. @dang can we update the link to the one above?

And there is already at least one other set of observations reported on arXiv from a September 2023 occultation. It's quite interesting, since the observations are a citizen science effort, with different observers from across Spain and Portugal (in this set) collecting data from multiple observers in multiple locations in order to map out the entire occultation. Part of the motivation was because of the upcoming Betelgeuse occultation and the potential to learn more about Betelgeuse from the observations:

> The stellar occultation by (319) Leona on 13 September 2023 in preparation for the occultation of Betelgeuse

> This represents an extraordinary and unique opportunity to analyze the diameter and brightness distribution of Betelgeuse's photosphere with extreme angular resolution by studying the light curve as the asteroid occults the star from different points on Earth and at different wavelengths. Here we present observations of another occultation by Leona on 13 September 2023 to determine its projected shape and size in preparation for the December 12th event.

[1] https://arxiv.org/abs/2309.12272

(Amazing that it was posted ~8 days after the observations were made!)

The Occultation folks had a presentation on these preparations back this summer:

https://occultations.org/publications/rasc/2023/2023Dec12Leo...

https://www.youtube.com/watch?v=ok7hJ_2DPhM&ab_channel=IOTAA...

It's also worth noting that if you're in a position to observe the occultation of Betelgeuse in December, you can and should participate. You need a DSLR camera in video mode for the light curve and a smartphone (recorded before and after) to accurately mark the time.

Bing AI's attempt at comparing the size of the star with the orbit of Mars:

Betelgeuse is one of the largest known stars and is probably at least the size of the orbits of Mars or Jupiter around the sun 1. According to the National Radio Astronomy Observatory, Betelgeuse has a diameter of about 600 million miles. The average distance between Mars and the Sun is approximately 140 million miles. Therefore, Betelgeuse is about 4.3 times larger than the orbit of Mars.

When asked not to compare diameter with radius, it said:

You are right. I apologize for the mistake in my previous response. Betelgeuse has a diameter of about 1.2 billion miles. The average distance between Mars and the Sun is approximately 140 million miles. Therefore, Betelgeuse is about 8.6 times larger than the orbit of Mars.

(For the reference, the radius of Mars' orbit is 228000000 km; the radius of the Sun is 696342 km, the radius of Betelgeuse is 764 times that, i.e. 532005288 km, which is about 2.3 times the radius of Mars' orbit.)

I'm never unimpressed when we can make these kinds of advanced notices. I know it's just math, but there's a lot of objects out there to run all of the simulations against to see what will be where when while in our line of view.

All stars are fixed point-like, basically static coordinates, so it's more of when one object encroaches another within a few micro-degrees.

3-body problem implies crazy perturbations and chaos theory and invoking of pendulum analogies, and all that's true, but due to the magnitudes of difference between human timescales and cosmological, we know the eclipses, occults, and all other matter of quirky alignment and other miscellaneous minute for millennia to come.

I can’t quite put my finger on why, but it blows my mind that its that “simple” in the sense that all the factors can be accounted for despite being incomprehensibly far away. My instinct is that there would almost certainly be some tiny unaccounted for perturbation that throws everything massively off over huge distances yet that’s not the case.

I can guarantee "simple" comes at the cost of (probably) multiple tens of thousands of pages of thrown away scratch paper (or equivalent) over many years and lives.

It is, it is just so far into the future that it seems trivial.

The Voyager spacecraft, when being gravity assisted by Jupiter, stole enough energy from it, that in 5 billion years, Jupiter will be 2 millimeters behind in its orbit around the sun.

All the stars we can see with our naked eyes are close enough to that, yes.

But you did make me think of this: https://www.eso.org/public/videos/eso1825e/

it's interesting seeing all of those stars in such random orbits instead a unified orbit where everything is going in the same direction. That one star really looks to be moving, and is pretty much the only way to know where the "center" is. Everything else looks like blobs floating in a petri dish.

I’ve been looking for a resource for a long time but haven’t found much. What I am curious about is how people 500+ years ago predicted solar / lunar eclipses (for example). Columbus was able to persuade some islanders that he was some sort of god by making the moon darken/turn red at a predicted time due to an almanac he happened to have.

Would I be able to make the same prediction using only math and whatever instruments could measure the positions of the sun and moon that accurately? What instruments and equations do I use?

If you're starting from scratch you would need some way to determine the apparent position of the Sun and the Moon. Probably some kind of long tube that you can rotate precisely. Ancient people would use buildings for that purpose. Then you need to make observations probably over several, possibly many, years to determine the Earth's perihelion and apohelion (at least their timing), the length of the year, and the precession. For the Moon you determine its orbital period and plane, and if you want to know whether the eclipse will be partial or total from a given location you also need the perigee and apogee (again, at least their timing).

Once you have all the data you find all the times when the Moon crosses the ecliptic plane (about once every 14 days), which are the only times when eclipses can happen. You discard the times when the Moon will not be aligned with the Earth and the Sun. You will be left with a handful of times per year when an eclipse is possible. If the eclipse is solar you compute the orientation of the Earth to see where it will be visible from. It's all trigonometry and linear algebra.

My understanding is that at Columbus time they did not measured sun / moon positions, but instead based their predictions on the eclipse cycles - if you have long enough record of past eclipses, you can notice that they are not random but the same timing sequence repeats after some time:

https://en.wikipedia.org/wiki/Eclipse_cycle

What are the odds we have a repeat of a substantial celestial object hitting Earth? Like devastatingly so, can that be quantified in some sense?

We have the (incomplete) track record of hits from the last billion years or so to extrapolate from.

Don't know that there has been much since that Dino Doom Rock 65m years ago?

Ever see notices of an asteroid making it's closest approach? Sometimes, those are closer than the moon is to earth. Sometimes, they're further out. There does exist a team tracking objects for the sole purpose of deciding if there is a potential of a collision path.

https://eyes.nasa.gov/apps/asteroids/#/home

Has some fun graphics to show what we know about. The scary part are the ones we don't know about. Some say that this groups budget is not enough.

The fact that our species is capable of doing stuff like this with math is the biggest gift handed to us by evolution.

That said, the thought that an asteroid passed between us and the moon is a stark reminder at how fragile we are. I hope I'll find photos of this on Google.

But if that asroid hit the earth, would've that marked the end of mathematics or does it just exist independent of our neurons?

Math is just a language for describing concepts that exist inside of our minds.

Fun fact, that's Bob Barkers 100th birthday

I’m guessing you googled the date or asked chatgpt for significant markers of the date, but I would choose to believe you just know this for some reason. The world needs whimsy.

And my 38th! Thanks for reminding me that me and Bob share it!

> An event like this is quite rare where the light from a bright star is blocked (or occulted) by an asteroid happening every few decades at most.

> a previous occultation of Leona in September 2023

Seems contradictory. Do they mean rare for any given star?

From what I can tell the star that it occulted in September was much too dim to be visible with the naked eye, whereas this is one of the brightest and most easily visible and distinctive stars in the night sky.

If you're accepting a dim star only visible through space instruments I imagine it happens near-constantly

Having it happen to a star you're actually aware of and can see tonight is pretty cool

The key word is "bright". It's clearer in the other article: https://skyandtelescope.org/astronomy-news/asteroid-will-cov...

> An occultation of a 1st-magnitude star is rare — such an event is visible from Earth only every few decades

and

> That changed on September 13, 2023: In advance of the December event, Leona occulted another object, this time of a 12th-magnitude star.

It makes sense: there are only a few bright (1st-magnitude) stars so occultation of them is rare, while there are a lot of stars in the sky so occultation of some (dim) star is not very rare.

————

Edit: We can come up with a more explicit expression. If each individual star has an occultation once every k days, then "at least one of N stars" has an occultation roughly once every 1/(1-(1-1/k)^N) ≈ k/N days. So if with N=22 (the number of 1st-magnitude stars: https://en.wikipedia.org/w/index.php?title=First-magnitude_s... ) this is once in 40 years (say), then with N = 10000 stars you'd see about once a month.

for checking this sort of stuff, Stellarium is amazing open-source doftware.

Betelgeuse falls under the “Ardra” nakshatra constellation in the eastern astronomical systems.

Q- is that the same day we will see it? I’m assuming the occultation is sufficiently close that speed of light considerations don’t have a material significance.

I didn't find any precise numbers, but the asteroid's orbit ranges from 2.5-4 AU out from the Sun. That puts it between 1.5-5 AU from Earth. Given that the event will be seen at night, it must be on the somewhat closer side currently. Even 5 AU is less than 42 lightminutes.

It's mildly distressing that only 5 AU is 42 light minutes

The speed of light is pokey, astronomically-speaking. It's like existence functions via telegraph in 2038, and everybody has to Google Morse tables

Give the simulators a break, maybe they haven’t filled their universe with computronium yet!

How do they determine when it's an eclipse, occult, or transit?

second paragraph here

https://en.wikipedia.org/wiki/Occultation

describes them all. Occultation completely covers the object, transit doesn't, eclipse requires a shadow.

I don't immediately see how you distinguish an eclipse and an occultation. If (visible, say) light from some source is blocked by an object, isn't that a shadow (albeit a very very faint one)?

For the lazy, is there a map already available somewhere which shows where on Earth this will be visible?

Available here: https://cloud.occultwatcher.net/event/1075-319-83995-648466-...

Narrower than the ones we're used to seeing for eclipses!

Zaphod would be quite happy.

I never expected I’d come to HN to learn about the study of the occult. TIL indeed.

'Occult' just means hidden. Where I am the .gov tests for 'occult blood in stools' of all people over 55, every two years. That's socialism, i guess, but i still do a double-take when i get the letter.

Occlude? Lol

“The term is often used in astronomy, but can also refer to any situation in which an object in the foreground blocks from view (occults) an object in the background.”

https://en.wikipedia.org/wiki/Occultation

You might want to become familiar with the use of the word as a verb instead of a noun. It might make you look less than whatever this makes you look.

Mention of occlude refers to the presumed typo “occult” in the title. Understandable question, given occlude and occult both work there.

If seems like the right thing to do is to look up "occult" in the dictionary instead of leaving a two word comment like "Occlude, LOL."

Of course, but it takes two seconds to find out that it's not a typo.

Yeah agreed, though the lol person obviously overlooked that!

It's funny to me that you still think it's a typo. There's still time to retract this

Evacuate? In our moment of triumph?

I dont: i think the person who wrote lol presumed it was, as i said.

Fwiw i had several years of Latin so the etymologies in this case are kinda fun.

Beetlejuice, eh

Beetlejuice

Occult and occlude are very similar, but they actually do not share a similar etymological origin. Occlude could definitely be used here, but the more appropriate astronomical word would be occult.

The etymological sense of occlude is that of closing off/blocking, while occult is covering/hiding.

Thanks. I’ve never seen the word occult used like this, your explanation was helpful.

> The etymological sense of occlude is that of closing off/blocking

That's quite the sense development for include, which I see derives from a word meaning "shut in, imprison".

"Occlusion" is also used in medicine, to refer to some tube or passage in the body becoming blocked.

Square... roots

Reply on news.ycombinator.com