Hubble Observes First Confirmed Interstellar Comet | Hacker News Reader

Hubble Observes First Confirmed Interstellar Comet

nasa.gov

181 pointsel_duderino71 comments

I hope we can get spectroscopy done on the tail! It would give us a really unprecedented look into the material composition of other solar systems.

The included video stated that the comet is composed of similar materials to those that make up our solar system. I am assuming they discovered that using Hubble's spectroscopy capabilities (STIS).

All of the materials would come from early nova/super nova. I'd wager we'd see a similar composition across at least the milky way.

Wouldn't we get the same composition from the spectral analysis of the suns they orbit?

Serious question, not a poke. I'm not an astronomy nerd and would love some education from a hn friend.

I’m not an astronomer, but I’d hypothesize that the composition of the non-solar objects in a solar system (eg. a comet) is different from the composition of the sun in that solar system.

The spectra we receive will include the absorption lines from passing through the stuff around the other sun and surrounding matter. I don't know how strong the effect will be, but it should be observable.

I wonder if it wouldn't be possible to launch a multitude of craft orbiting in various places around the solar system and just stay primed and ready to intercept and explore these surprise interstellar visitor objects? Is it impractical to achieve this with something like a long-burning ion propulsion system?

These things are really unique and it's not like we'll have any other way to explore something up close from outside the solar system

I was questioning myself the same question, and imagined that would be a perfect application for a surveillance system with 3 satellite placed at L3, L4 and L5 Earth-Sun Lagrangian points and 3 placed 120° from each at a perpendicular orbit with respect to Earth orbital plane.

Sadly you will be met with the same arguments that have been brought out since before the time of the moon landing. Why? The money is better spent on maintaining our military advantage over other counties. It’s better spent on housing programs for the poor. It’s better spent on upgrading our crumbling bridges and roads. It’s better spent on new infrastructure like trains and nuclear plants.

The list will be endless and all of these people are right. Their world views are no less correct than yours and their interpretation of how our shared resources should be spent equally correct.

This is why capitalism is so effective. This is why Monarchies we’re so effective. These systems exist to channel the theoretical 1,000,000 humans away from spending all of their resources advancing 1,000,000 goals a single unit and instead advance one goal a million units (monarchy) or 5 goals 200,000 units (capitalism).

Speaking more to the topic at hand, it’s great that we were able to make the progress that we have and let’s be honest that’s owed almost entirely to the moon race going public (same way gluten free everything is available now making the people that really need it very happy because they never would have received nearly as many units of productivity spent on advancing their problem if it hadn’t gone mainstream for a time).

Shouldn't "monarchy" be compared to "democracy" instead of "capitalism"?

The economic model pertains to a whole different plane, isn't it?

In this instance no not at all. I can compare the sun to a box of Cheerios based on that fact that both are yellow and bringing the moon or Fruit Loops into the conversation because you missed the context is “yellow things” is not appropriate. Democracy has no place in what I am discussing.

Monarchy and capitalism are both drivers of aggregating individuals labor into a small number of goals. Socialism and Democracy are both sources of driving individual labor into individual pursuits.

Only the eye of the beholder can determine what is good or bad. A socialist democracy is most likely incapable of putting a man on the moon. A capitalistic monarchy is most likely capable of solving poverty within its borders (be careful what you wish for as you may be determined to be part of the cause of poverty and excised for the good oc The many).

China is capitalistic monarchy and so far it doesn't look like they are solving poverty.

Anybody else remember when Halley's comet and Hale-Bopp were in the sky at the same time? It was one of the most amazing things I'd ever seen...

No. Hale-Bopp was discovered in 1995 and became visible in 1996. Halley was last visible in March 1986.

Can we even assumed that this comet is from or has encountered another solar system?

Since the observed composition of the comet is mentioned as being "remarkably" similar to solar system comets isn't there any possibility at all that it could indeed be from within our system? Can no combination of freak gravitational nudges/slingshots, however unlikely, result in the observed orbit?

That’s a great question, and it’s (relatively) feasible to answer. The object is coming in towards the center the solar system, so its past trajectory lies outwards. If it has been disturbed into this path from a hypothetical sun-centered orbit, it would have to have happened very recently: otherwise it would be long gone, never to return. So it would be necessary for the back-projected trajectory to pass very close to a compact, massive object. Dare I say that the vast majority of all such massive objects in the solar system are well known; so if the trajectory doesn’t indicate a close encounter with a planet within the past decade or so, then this possibility is essentially eliminated.

There was a recent paper that showed it is possible planet 9 is a primordial black hole - would that work?

https://phys.org/news/2019-09-planet-primodial-black-hole.ht...

No, that paper says "What if Planet 9 is a Primordial Black Hole?" and then works out some consequences and finds them to be not ruled out. It doesn't start from observations and arrive at the PBH in any natural way.

To judge for yourself hour serious the authors are in proposing a primordial black hole to explain the anomalies in the outer asteroid belt, I refer you to figure 1 in their paper: https://arxiv.org/pdf/1909.11090.pdf

Would you pass an opportunity to include illustration of an astronomical object at a scale of 1:1?

I stared at that figure for about a minute and wondered at how friggin' satisfied they have to have been about it.

It was and is really neat, even if the likelihood of its reality is low.

Right - that's why I worded my sentence "it is possible planet 9 is a primordial black hole"

That, or a spare comet prop accidentally dropped from the Oort catwalk that surrounds our solar-system-scale Truman Show /s

If the aphelion (furthest point of its orbit) is significantly farther out than the Oort Cloud, then it fundamentally can’t be from anywhere inside our solar system per orbital mechanics. And in this case, its “orbit” is hyperbolic. Meaning it’s going faster than the escape velocity, so will never return.

It’s also a dead giveaway if the eccentricity or direction of its orbit are significantly different than those of the rest of the solar system

Edit: For objects as far out as the Oort Cloud, a few relatively small changes in velocity can actually result in hyperbolic orbits. The real distinction is a big difference in velocity.

Unless it interacted with other bodies in the ort cloud. If we consider three-body interactions, slingshots, most any trajectory/orbit might be possible.

It depends on interobject density and single object mass, I'd reckon.

Having it redirect the orbit at velocity might be astronomically (!) low

Also, I don't know it's trajectory relative to the solar plane; it might be ruled out by that alone

From Wikipedia:

"2I/Borisov also has a hyperbolic excess velocity of 32 km/s, much higher than what could be explained by perturbations, which could produce velocities when approaching an infinite distance from the Sun of less than a few km/s"

> An artificial satellite also crosses the field of view

Can anyone give some hints on how to spot it? Maye it is really evident, but I was not able to identify it.

I am interested in the fact that an amateur astronomer discovered this and have some subject matter questions. What type/size of telescope would be required? Is this the result of simply arbitrarily scanning night skies? Do amateurs use software of some sort to aide in locating sky locations where undiscovered objects might be? When you do think you’ve found something how do you report it? Do amateur astronomers gravitate toward any one social site, i.e. is there a vibrant Twitter community or subreddit? Was/would Gennedy (and amateurs like her) working in coordination with a group of others (local or distributed).

TLDR I want to discover a space object. How do I do this?

You may want to check out the forum site Cloudy Nights.

Here's a thread in the amateur telescope subforum about the instrument that discovered this comet. There's a photo of the telescope and of Borisov four posts in to the thread. https://www.cloudynights.com/topic/677286-homemade-065m-f-15...

That particular subforum is full of people who make their own telescopes in their home shops, and it's a fascinating place to visit. From what I can tell, this particular telescope is an extreme example, an instrument manufactured to professional standards by a well-resourced optics professional working in his spare time.

Yeah. I would like to know this too. The process of this, how to start this kind of things as a beginner.

This is so cool!

I love seeing the influence of amateur astronomers, like in this case.

This is quite serious. Interstellar objects travel at very fast speed. Comets, because of their highly elliptical orbit, already impact earth at much higher speeds than asteroids. Can only imagine what a hit from something further than the Oort Cloud is.

It is very likely that the global flood monomyth is based on the impact of a comet around 13,000 years ago. This was somewhat discounted only 10 years ago, but now is more than the majority consensus in the field (“Younger Dryas Impact Hypothesis”).

Comet would have hit Greenland by the way, with many pieces falling apart and hitting North America. This would have destabilized the entire ice shield across that area.

> This was somewhat discounted only 10 years ago, but now is more than the majority consensus in the field (“Younger Dryas Impact Hypothesis”).

Is it the "majority consensus"? The hypothesis' Wikipedia article (https://en.wikipedia.org/wiki/Younger_Dryas_impact_hypothesi...) has links to multiple recent articles arguing against it (in both the "Evidence" and "Criticism" sections), including ones like https://www.sciencemag.org/news/2018/11/massive-crater-under... suggesting that the Greenlandic impact event might have happened at the wrong time or not produced the widespread effects you and other proponents of the hypothesis suggest:

> Even if the asteroid struck at the right moment, it might not have unleashed all the disasters envisioned by proponents of the Younger Dryas impact. "It's too small and too far away to kill off the Pleistocene mammals in the continental United States," Melosh says. And how a strike could spark flames in such a cold, barren region is hard to see. "I can't imagine how something like this impact in this location could have caused massive fires in North America," Marlon says.

Lots of majority consensus ideas have papers criticizing them, and I don't see why Wikipedia would be a good place to look to determine that in any case.

The Wikipedia article doesn't agree with your assertion that this is "more than the majority consensus in the field", and presents lots of evidence against the hypothesis.

A more likely explanation for flood myths is that all ancient civilizations lived on the banks of mighty rivers that occasionally flooded.

Dunno, that seems a bit to regular. Humans weren't that stupid and rivers change all the time.

Seems much more likely it's something really unusual. Like say the Mediterranean basin and the resulting Zanclean flood. Back before humans were in North America it was a giant fertile basin with numerous rivers. Then one river that happened to come from the Atlantic ocean started to make some progress with erosion and kept getting bigger. The feedback loop turned into something that embarrasses Niagara fall by many orders of magnitude.

If you lived in the Mediterranean basin this would have made quite an impression. I believe this event was well depicted in https://xkcd.com/1190/ or https://blog.xkcd.com/2013/07/29/1190-time/

As big as that mega flood was, there have been others and certainly seems like very good source material for the numerous flood myths.

That flood is terrifying btw. I can barely watch the 3G geographic movie models without feeling terrified. That would have been 5 million years ago though I think. The #1 rule of humans and archaeology and anthropology is whatever your dates are, it probably happened sooner :)

But tough to imagine that flood could have been it (although amazing story) and agree with your final paragraph.

How does a comet cause a global flood? I couldn’t find any hypothesis regarding the link between comet impact and a global flood

It would not create a true global flood but it would create tsunamis and weather disruptions that could certainly by mythologized as such. Since humans are egocentric we would naturally assume it was our fault and that we offended the god(s).

There is no difference between a comet and a asteroid in this kind of situation, both would cause tsunamis.

On the other hand, having a huge fireball in the sky, earthquakes, ash falling from the sky, would probably leave an impression along with the tsunami (flood) that would be in the flood story. I seriously doubt the flood stories came from an asteroid or comet impact. Much simpler explanation is that it is a memory of either Black Sea forming or memory of the sea level rising at the end of the ice age.

Find some tsunami videos, the water just keep coming. A comet would produce a big wave.

> Can only imagine what a hit from something further than the Oort Cloud is.

Such a hit is extremely unlikely, extremely being a severe understatement. Imagine a solar system as a target, the size of a Mars orbit. If a fast-flying object from outer space manages to hit that target, its probability to hit earth is... 0,000000078%

If such objects will enter our Solar system every year, I'd say we're likely safe for the next few billion years. Sun turning into reg giant is a much more urgent issue.

What? The article makes no mention of the comet coming anywhere near the Earth. There is literally nothing to worry about here.

This might be a dumb question but how does a comet reach 110,000mph? From an explosion + slingshotting off gravity?

It’s from interstellar space, and not from our solar system. Virtually all of this speed is simply from it being in a different relative reference frame to ours.

Great but old video about frame of reference.[1]

Is the comet coming towards us or are we going towards it? Does a dropped ball fall to the earth or are we going upwards to meet it?

[1] https://youtu.be/lbnDSdrriGI

It's relative to the solar system. The solar system itself is traveling at 514,000 mph relative to the center of the galaxy.

I find it weird when people quote large velocities in mph.

Sure, we measure normal things in mph, but who has a reference point for 500 thousand mph?

Whereas, I, and I would have though other people, have a general idea that rockets and such travel at a single or low double digit mi/s, and (maybe it's just me) I would think the speed of light at about 186 thousand miles per second is well known.

Probably just gravity+the relative velocities of it and the sun. That’s about the orbital speed of Mercury, so it’s not an insane speed.

actually it's almost exactly Venus' orbital speed.

You sure you're using the right units?

it's like 70%, more than certainly the same order of magnitude. each planet closer to the sun has to zoom faster than the one before it, to not fall in

I'm aware of how orbital mechanics works, but I brought up units specifically since 70% is close to the ratio between kilometers and miles. The orbital speed of Mercury, for reference, is much closer: https://www.wolframalpha.com/input/?i=orbital+speed+of+mercu...

Initial velocity as it entered the sun's influence, plus acceleration from the sun while under that influence.

The Parker Solar Probe will hit 430,000 mph as it falls towards the sun, for example. https://en.wikipedia.org/wiki/Parker_Solar_Probe

if I understand correctly that’s not extraordinary fast. NASA has sent things over 150k mph.

Oh interesting, you're right the Juno spacecraft went 130,000mph. Fascinating.

https://en.wikipedia.org/wiki/List_of_vehicle_speed_records#...

I'm honestly kind of surprised to see people using miles per hour for measurement of speeds in space. I guess I should specify how many leagues my car can travel per hogshead, as well.

I'm from Canada but the article used MPH so I kept it. I'd rather not convert every number I copy/paste.

Plus everyone gets the gist of what mph means. It's common sense.

Orbital velocities are generally quoted in miles per second or km/s, and so is the speed of light. So mph tends to lack context.

Does this mean we will only see one pass of this comet? Or did/will it get captured?

In this case, a hyperbolic trajectory means the orbit isn't closed, which also means the the object's velocity is above escape velocity. The only thing that would possibly change it to a capture scenario would be an extremely close pass to a planet, which theoretically could drain off its excess velocity and would then wind up in some sort of elliptical closed orbit.

Since an encounter like that is easy to predict once a trajectory has been calculated, and there's no mention of it doing so, I have to assume it's going to cruise in, pass its closest point to the Sun, and zoom right back out.

So that means this is incredibly historic, yes? We have only witnessed one other interstellar object and we did not learn about it in time to make meaningful observations?

It's historic in the sense that it's one of the first interstellar objects we've seen. But these things are almost certainly not rare; they only seem so because we've only recently become able to detect them. In 10 years sightings of interstellar objects won't even make the second-tier news feeds.

When my mother was born plate tectonics was a hypothesis. When I was born proof of extra-solar planets did not exist.

I know this these objects have been hurling past us for billions of years, but the fact that we spotted one is exciting for me.

Yes. One pass only.

While Oumuamua was a sentry buoy this ‘comet’ is a confirmation device shielded as ‘interstellar comet’. I wonder who shows up next? This sectors silicon based AI wiping out carbon life forms? Just kidding... hopefully we get to see more of these interstellar objects in the next few years. Exciting!

Is this one less weird (interesting, unique, etc.) than Oumuamua?

It is interesting in that it is only the second confirmed interstellar visitor. It is less weird in that it looks like an ordinary comet, while the first object is much more unusual.

No, this is one is just confirmed as far as I can tell.

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