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Astronomer here! AMA!
I'm here on the invitation of someone else, and not sure what this new website is all about yet/ the space stuff seems pretty scant, so anyone got a question about space they need answering?
For those who don't know me from the certain other website, I am a radio astronomer currently at the Center for Astrophysics | Harvard & Smithsonian. Known under this user account on a certain other website for comments that begin with "astronomer here!"
Hey! Welcome to tildes! Though I’m not sure I can yet say welcome, as I’ve also been here less than a week.
Regardless it’s nice to see people who produced quality content on Reddit move over!
To stay in the spirit of the thread, I live in a pretty dark area of the world. I’ve long been interested in getting a telescope, especially now that I have a daughter and another one on the way. What is in your opinion a good mirror size that would work well to show the wonders of space?
I think it's important for a first telescope to not get something TOO big because it actually makes things harder in some ways to find things (smaller field of view). I think a 6" telescope is a great starting size that's gonna get some "wow!" factors, 6" referring to the diameter of the mirror.
Moon and planets are of course awesome first targets no matter where you are, but I highly recommend anyone who gets a first telescope to also get a copy of a book called Turn Left at Orion to help find the deep space stuff. Not only is it an excellent guide to how to find things, it's also got pictures of what the things will actually LOOK like through a small telescope. Really an invaluable tool to learning what's out there! Have fun!
Thanks! That’s very helpful!
As someone keenly interested in space but basically ignorant of observation techniques, I bought a pair of binos to try to see the recent comet. I was shocked at how difficult the observing actually was - should definitely have gotten a tripod.
Obligatory "not OP but..."
Every time I've seen recommendations for a first telescope, Dobsonians are always recommended. They're bulky, take up a lot of space, and are awkward to move around, but you really can't beat what you get in terms of viewability. Even an 8-inch Dob will enable to you to see a ton, especially if you're in a dark area.
I've been looking at Cassegrain's (or variations of them) for a long time to upgrade to (from my Dob), as something more compact, but those are $$$$.
Hey Andromeda, so glad to have you here! Heh, I was actually using you as an example the other day, when talking about higher-quality comments that we used to expect on a certain other website. But enough about that, let's get to my question!
We all know there's a huge amount of potential discovery on bodies like Europa or Callisto, and in a perfect world NASA and other agencies would have unlimited resources to be able to pursue them all. Unfortunately, that's not the case, and this means that in our lifetimes, there are missions of this kind that will simply never come to be.
Which of these kinds of space missions are you most excited about? What about most disappointed? And if you had the ability to plan your own, what would you be most interested in?
It's interesting that you mention Europa as an example, because there are actually several great missions going there in the next few years! The European Space Agency is one of them, and NASA is launching Europa Clipper next year- https://www.jpl.nasa.gov/missions/europa-clipper (It will take a few years to get there though- space is still big, funding or no)
Personally I think one fascinating but neglected area of the solar system are Uranus and Neptune- they're just really far, and tough to muster much enthusiasm for (and, in the case of the former, I think astronomers are all tired of the jokes and no one wants a career based off them). They haven't been visited since the Voyager missions in the 1980s, and our knowledge of planets have changed so much since- we now think Neptune formed much further in, for example, and that its biggest moon Triton is actually a captured Kuiper Belt Object. You could learn so much about two completely different objects if you did a mission that went into orbit there!
Obscure is obviously a bit subjective. However, it is strange what a gigantic game changer radio astronomy is about to undergo in the next decade that most laymen have never heard about, thanks to the Square Kilometer Array (SKA) currently under construction in South Africa/ Australia, and the next generation VLA (ngVLA) which will soon begin construction in North America. These are going to revolutionize radio astronomy thanks to both the increase in sensitivity and the cadence of observations- I can't wait!
No, the NSF has decided to divest from Arecibo and they are currently taking apart the remaining ruins at the site. (They were required to do so at any point when Arecibo stopped being used.)
Arecibo was indeed the only telescope capable of transmitting and receiving, which was useful for some things like mapping asteroids via radar, and is a capability FAST doesn't have (because, honestly, it's a pretty edge science case). It was also a very important baseline for things like nanoGRAV, which are looking for gravitational wave signals by using pulsars. But radio astronomy just isn't a field that gets a ton of money, unfortunately.
Glad to see you here! I've always been a huge fan of your "astronomer here" comments, so it's exciting to see an AMA.
Perhaps a little bit of a shallow question, but coming from someone whose always had a healthy (albeit casual) fascination with the cosmos, where would you recommend someone start if they wanted to turn their interest into deeper knowledge? I studied a fair bit of physics at university, but am always surprised about how little I actually know when watching the Astronomy on Tap lectures at my local brewery each month. Trying to fully digest some of the whitepapers I've read makes it clear I'm lacking significant prerequisite knowledge, but most internet resources I come across skew toward either ELI5-level or PhD-level material. My partner does his best to ELI... well, me, but I'd love to capitalize on this willingness I have to learn.
I mean, honestly? Poke around on Wikipedia. The amount of expertise on there and detailed articles is insane and I (along with other experts) rely on it alllll the time.
If you want more than that though, there are definitely great free courses on places like coursera!
Ello and welcome!
Resident cosmologist @gpl had a nice AMA the other day here --
Can you ELI5 the difference between an astronomer and a cosmologist? Where there's intersection and where they differ, and sort of, "when" along discoveries and such do each come along? Other related professional titles lay people aren't aware of?
A cosmologist is a type of astronomer (or astrophysicist- they're essentially the same thing today). They specialize in studying the big-scale structure of the universe and the early universe, aka the cosmology of the universe.
Does radio astronomy have any issues with the proliferation of leo satellites that other forms of astronomy have to deal with?
Yes. In some ways it's WORSE because while an optical astronomer is affected when a satellite goes through their field of view, a radio astronomer can get swamped if the satellite is just plain above the horizon if you're observing at that frequency.
Unfortunately, this is just going to be a bigger problem as time goes on.
Is there an consensus fix that astronomers would like to see?
Some sort of international regulations regarding satellites/ mega-constellations, similar to what we do in spectrum allocation now. The sky is a shared natural resource and I don't buy the immediate argument that we all ought to give it up without considering the ramifications of doing so.
My concern would be that there isn't enough public and/or commercial interest in preserving the sky for astronomy, and that this would produce regulations that little improve the current situation. But perhaps that is too cynical of me.
I'd have to agree here, I don't think most of the public would care until it became a visible problem for them, and perhaps not even then. By that point I imagine the effects on ground-based astronomy would be devastating.
Is there any talk or work being done around this, for example software filtering (but then the overhead that comes with that, false positives, etc)
Oh, we already do this- radio frequency interference (RFI) of all sources has plagued radio astronomy since its inception, and this is just one of many forms of it. I even wrote a PhD thesis chapter on automatic RFI flagging so I know a thing or two about it!
Most of the time, if you do filtering that's gonna get rid of the RFI... but if the RFI is around for a significant amount of time compared to the length of your observation, what's left will not always be sensitive enough to detect your signal. To use a non-satellite example of RFI, I often do observations at 1-2 GHz with the Very Large Array (VLA)- a range called "L-band"- which is where a lot of cell phones operate. If someone driving past the VLA does not turn off their cell phone, that ruins the data for that amount of time because a cell phone on the moon would be one of the brightest things in the radio sky- one right by the VLA is enough to swamp the telescope! I usually calculate my time request including RFI overheads, but often that's still not enough, and if I lose the data bc of that it's just tough luck.
Note to self: turn phone off when driving from Albuquerque.
It's actually like 2 hours drive from Albuquerque, an hour or so west of Socorro, in a dried lake bed surrounded by mountains. You're really probably ok unless you're on the highway LITERALLY going right by it.
I don't know much about astronomy, but reading quality content from qualified people is always a joy!
What is your favorite 1-2 sentence fact/ piece of trivia you have for people who nothing about your subject?
Sharks are older than Saturn's rings! Sharks have been around for about 400 million years, and recent data shows Saturn's rings likely formed just ~100 million years ago or so.
do we have any good models predicting how long saturns rings will be around?
Probably another 100 million years or so- https://solarsystem.nasa.gov/news/794/nasa-research-reveals-saturn-is-losing-its-rings-at-worst-case-scenario-rate/
Which is really a blink of an eye if you're thinking about the age of the solar system, 4.5 billion years. We are so lucky! No way Saturn would be half as cool if it didn't have the rings.
Wow, so Saturn's rings will only have a life of about 200 million years?! To make this make more sense to me, I equate this to geologic timescale. 200 million years ago was the early Jurassic. The lifetime of Saturn's rings will be similar to the time from the Jurassic until now.
The Jurassic may seem like a long time ago, but it's almost "recent history" when you consider the timescale of the earth. It took billions of years to go from an inhospitable rock with no life --> to microbial life forms --> to simple plants/animals/fungi --> etc, etc --> to dinosaurs. 200 million years is so small comparatively.
Anyway, as someone who finds astronomy interesting, but isn't very knowledgeable of it, geologic timescales help make soo much more sense to me.
How much creedence do you put in the idea that the rings are formed from a moon that shattered? I've seen comments where people say there's a lot of evidence pointing to a catastrophe in Saturn's system but I don't know enough to know if its true or not.
I actually went to a seminar once on this topic by someone who's researched it, and they made a really compelling case for the theory! It really does answer a lot of the outstanding questions. Here is a video of what his theory looked like when the collision happened- https://www.youtube.com/watch?v=UtVnftTd1tA
There's a thing I had heard of before, called Project Starshot, which wants to send probes to other solar systems by using a solar sail and using land based lasers to propel it to near light speed.
Is this something that is seriously being pursued?
Short answer, not seriously. There is some private funding to developing the ideas behind it, but nowhere near what would be required to see this happen. Worth noting that solar sails in general though are a thing, and have been launched several times! https://en.wikipedia.org/wiki/Solar_sail#Projects_operating_or_completed
Also, there's just practical considerations to think about when it comes to Project Starshot. First off, congrats you're at the speed of light... how are you going to slow down to see anything? No laser on the other end! Second, the idea behind these projects is usually that the probe is super duper tiny... so tiny that we have no way of transmitting and sending any info back from another star system.
Yeah, that's a good point. I did some simulations in grad school for what the ground laser might need to be effective, but I had been wondering about how useful a probe like that would be.
Hi, thanks for this opportunity! Are there any new developments, discoveries, or studies that you are very excited about? Since the release of the James Webb, have there been any discoveries that challenge your field’s understanding of any subjects?
I'm pretty excited about this paper I'm trying my hardest to submit to the journal. Last fall I announced the discovery of a black hole that shredded a star, then about two years later began "burping" out material at half the speed of light. We got a bit of press about it, which was cool! But that was just one object in a sample of about two dozen, and now I am going to publish the results about the rest of them...
JWST is cool, but no, hasn't affected anything much in what I do yet. My focus is on transient radio signals- things that change over time instead of being constant, like from gigantic space explosions- and there just hasn't been much overlap.
Your paper sounds incredibly fascinating!! I was under the impression that nothing escapes black holes once they are "sucked" in, not even light! If I may ask another question: how can you tell that what's being ejected is actually the consumed star?
The trick is things can't escape a black hole when they pass the event horizon. This material did not- we think it was in an accretion disc or similar outside the black hole, and then for reasons we don't understand began flowing outwards.
As for how we can tell it's related to the star, we know from other wavelengths (mainly optical) that the star got shredded- these are events that become brighter than supernovae so hard to miss. If it was something like a second star that got shredded since the first, we would have seen a similar flare, but we do not.
I can't really think of a question right now, but just wanted to say I'm so glad you're here! I love reading your comments on r/space and have learned a lot from it. I'm a big fan of your posts!
Do you plan on doing the same thing here?
I suppose we'll see how things go? Like, my goal for this account, both here and on Reddit, is outreach and sharing my love of space. For that reason unlike many of you I have not nuked my Reddit account and still maintain it, with no plans to abandon it, because that is still a far bigger audience for outreach and I get more out of it existing than not for my goals. (But obviously if you've chosen to do something else I understand that.)
I anticipate Reddit being like Twitter, in that it's not as good as it was a year ago but still the best at some things, so people keep their accounts. And like Twitter over the last year, there are several splinters now and I'm checking out how each one is and to see how they're doing (frankly though, I don't find any of the Twitter alternatives great and don't log in much). So in that context, still poking around this community in general and seeing what it's like, no promises just yet on how often I'll post but for now this AMA is fun.
Hope that somewhat answers your question!
Edit: my biggest complaint about Tildes right now is the rate limit for new comments is WAY too low for something like an AMA- I'm now all the way up to waiting 5min before responding to anyone! :( I know it's a new account, so maybe it goes down, but right now it's a bit frustrating.
Thank you for answering!
I didn't nuke my Reddit account either because I think there is a lot of good information on Reddit that would be lost of everyone did that. And it's not just for educational things. Sometimes you post some strange personal issue with no answers, and a year later someone finds that post and messages you because they need someone to talk to.
I think Reddit will be worse from now on, but it's not worth the loss of more than a decade's worth of knowledge.
The rate limit does sound annoying. I tried looking that up but I can't seem to find anything about it.
A silly question and a bit of a cliche, but I'm genuinely curious if it happens. Do people confuse your profession with astrology often?
It happens sometimes, but not as often as the Internet seems to think! I mean to be fair I'm also not hanging out as much with people in my daily life who'd do that much.
Your username is my favorite space object :-) Have had a poster on my wall of it for at almost 30 years and it always brings me joy when I can find it with my binoculars.
Anyways, I don't have a space question as such, but want to hear if you have a favorite science fiction story, movie or book? Does something exist that portray your field of research the best?
I mean, I basically became a radio astronomer because of Contact by Carl Sagan, so that one! :) I think both the book and the movie are worth checking out, great but in different ways.
Me cosplaying Ellie Arroway on the job
Ha - that's great. That is also one of the best works in the genre.
There were times when I though about buying telescope to look at night sky through. The thing is I don't really want to give in the money for it.
Are telescopes that cost 100€ worth it? What about some for 200 or 300€? I suppose kid toys are near unusable waste...?
Is there some money threshold? I mean with notebooks/laptops it's simply "don't think about buying anything under 500€ as it will be junk" - is there smething like that with telescopes?
And one other question - Do you play Kerbal Space Program? Or some atronomy related game?
So, I don't know if it's kosher around here to link to Reddit, but there's no way around the fact that the best resource I know to answer this question on the Internet is this beautiful guide to buying a telescope from /r/telescopes: https://www.reddit.com/r/telescopes/comments/z9s352/beginners_quick_guide_to_choosing_your_first/ So go find a cached link of it if you don't want to drive traffic there, because frankly as a professional astronomer I don't know the ins and outs of the current amateur telescope market and those people do!
As for astro related games, no sorry, when I get home after a day of astronomy I like to indulge in my other hobbies! (I'm also not much of a gamer in general.) I do do astronomy cross stitch though...
I tend to not open Reddit anymore but it still is the source for many such information. Thanks for the link, seems like I could buy at last good starter telescope for around 200€ (equivalent where I live). Good to know that even such cheaper options are actually usable. I knew I wouldn't be abke to buy decent one for 50, but was curious where the line is.
And it is ok to link to Reddit. Tildes community is partially madeup by Redditors who are left homeless, which doesn't mean they do not miss their former home. There is no anti-reddit guerilla movement here, although people don't like the way it turned out so far.
What are your plans? Are you leaving Reddit? Or is Tildes like a temporary shelter? It's not aout astronomy, but it kinda is sharedinterest I guess :-) I have made up my mind and won't be coming back, I will stay here.
I have no plans to leave Reddit at this time. My goal is to do astronomy outreach, and while I can't say their actions of recent weeks were awesome it's still gonna be a huge platform going forward and I intend to use it to share my passions. (Also, there's just some resources that have no equivalent elsewhere online, and I don't want to get rid of. Like, I'm 20 weeks pregnant right now, and the private pregnancy subreddits are some of the most wonderful communities you can find for support with no equivalent elsewhere online, and would have a definite negative impact if I left right now with nothing to replace it.)
I anticipate Reddit being like Twitter, in that it's not as good as it was a year ago but still the best at some things, so people keep their accounts. And like Twitter over the last year, there are several splinters now and I'm checking out how each one is and to see how they're doing (frankly though, I don't find any of the Twitter alternatives great and don't log in much). So in that context, still poking around this community in general and seeing what it's like, no promises just yet on how often I'll post but for now this AMA is fun.
Except one thing- I am now down to only one comment every 5min because I'm posting too much. New account, I know, but still this is a bit frustrating for an AMA when you want to respond to everyone! :(
I raised the commenting rate limit on your account, you should be fine now. Thanks for the ping, @Pavouk106.
... I just had to wait another 5min to tell you the rate limit is back. :( Maybe it automatically resets?
Hmm, strange. It might take a short time before the new ratelimit takes effect for some reason, let me know if it continues stopping you for much longer.
Thanks!
I haven't come into this limit yet. But I didn't do AMA as my first action :-) Contact @Deimos and ask if the restriction could be removed. If it can, I think it as well might in your case.
ooh, have you shared any of those? Or alternatively, know any nice patterns?
Here's probably my craziest one- https://twitter.com/whereisyvette/status/1134170275212341248?lang=en
If you want nice astro patterns, check out Climbing Goat Designs! She does a ton of great astro stuff, I've made several of them.
What kind of resources would you point folks to who desire to get into amateur astronomy? I am thinking groups to connect with locally, online resources, tips on first telescope purchase, and etc.
I'm not an astronomer, so maybe OP will have better advice regarding local clubs. But I've found that librarians are often very helpful if you're looking for local hobby groups. They're often very connected with the community.
What are you researching these days? Any recent papers you’re particularly excited by? Welcome!
My research focuses on transient radio astronomy, which means signals that turn on and off instead of being constant. In practice this involves gigantic space explosions, like supernovae or a black hole that shreds a star! My most recent discovery in this area got a bit of press last fall- https://arstechnica.com/science/2022/10/black-hole-belches-out-remnants-of-gobbled-star-years-after-initial-meal/
I'm so happy to see you here! I've been following you on Reddit for the last couple of years and always enjoy your posts! I hope to see much more from you on here on Tildes🙂
Welcome! Thank you for being here.
My joke question is, have you seen any funny floating objects lately?
My serious question is, would you happen to know if it is possible to "override" the mass of a particle for any amount of time, and then return it to its original mass and state? If so, is it possible?
My cats can launch projectiles in very funny ways, but not sure if I'd buy that they "float." :)
We don't think so, it appears the masses of particles are hard-wired fundamental constants in the universe.
Totally offtopic, and not a question... but I just wanted to say thanks for doing this, and welcome to Tildes. :)
Also, this (and the other awesome AMAs recently (e.g. @gpl's I am a cosmologist, AMA) has inspired me to add this feature request to Tildes Gitlab: Add a Q&A comment sort to help facilitate AMAs
Have you read the preprint from Saio et. al. that suggests Betelgeuse is in the late stages of core-carbon burning and may only have decades before going supernova? It seems pretty exciting, but of course with the usual caveats about it being based on our current models of how stars function and that the dimming in brightening is what they say it is - Any interesting insights you might have as an astronomer?
My insight in it is that every other astronomer in the field thinks they made serious errors in their analysis- here is one such response, with accompanying Twitter thread here by an astronomer explaining it all.
Short answer is they did basic things like cherry picking the size of Betelgeuse from papers that explicitly said not to do that, because those numbers matched their analysis. Not very scientific!
What's your favorite place to read astronomy news?
I mean, as a scientist I go to ArXiv.org every day and see what's printed. Then I will say astro Twitter and /r/space usually cover everything I missed.
I once read a theory that planet earth was positioned so far from everything that space aliens looking for life on other planets were unlikely to bother checking out such a far-away place. Is there any truth to this?
I mean, we don't know for sure because it's not like we know if aliens exist, where they are if so, and what motivations they might have. BUT I can tell you that our Solar System is really not located in an off-the-beaten-path patch of the galaxy or anything like that, so I'm not sure I buy that argument at face value.
Thanks, it's been a few decades since I read it in some sci-fi zine and I always wondered if the science held up.
Say my birthday was in June and mercury was in retrograde that day, what would be the chance that....
Sorry, had to do it.
Now serious question, what would you recommend to someone in Central America to look for in the sky?
Venus is just beautiful right now in the evening sky! Look west about an hour after sunset, and the really bright "star" in that direction is Venus. You can't miss it. :)
You have 30 minutes to convince a flat-earther that the Earth is a sphere otherwise you'll die a painful death. You have access to every information known to men as well as the means to display it.
Go!
If there was an edge, real estate there would be phenomenal and in high demand!
Otherwise though, never argue with stupid people- they will drag you down to their level and then beat you with experience.
Good point! I did edit my comment while you wrote yours, maybe you like the better conditions?
No, not really. It's tough to argue anyone out of a position in 5 minutes when they aren't approaching in good faith to begin with.
Regarding flat earthers, I liked the youtube video In Search for a Flat Earth It gives a good idea of the mindset of those folks.
What attracted you to space as a career?
I read a book about astronomy when I was 13 years old, and I've never wanted to be anything except an astronomer after that point. I love stories, and the story of our universe is the biggest one we have!
In the context of JWST? We're going to learn SO MUCH about the early universe that we don't understand right now. This is already happening, but still on a small level where we don't have the details pinned down.
Thanks for joining us :)
I did a little googling to try to ease your load and came up empty handed.. lol
I can understand how temperature, and composition can be determined, but how size is determined has always stumped me. I get that newton's gravitational theory can work, but you still have 2 variables and 1 equation!
So how do you determine the size? Do you have to use the inverse square law to get the distance to it, and then use the angular diameter?.. idk! I'd imagine that might have it's issues too.
Thanks for your time, and again welcome :)
You can't figure out the size of something in astronomy in a simple way like you've described, you need something else to break the degeneracy. That's why often in astronomy you hear about the mass of things but not their size. Examples on how to do this:
I'm sure there are a few others too but those are the most common methods.
I don't have any questions but it's nice to see you here. Always loved your content and your passion for astronomy.
The site isn't that new. It was made by the only good developer of reddit after they had a fallout and he left some years ago. It's flying under the radar by design.
The question is this: Given that God is infinite, and that the universe is also infinite... would you like a toasted teacake?"
Potentially Starship/SpaceX will disrupt current cost/size limitations. What's the bluesky potential for space telescopes? Would an even larger telescope at L4/L5 or larger volume in various orbits, essentially put earth telescopes out of business?
I think it is fine to say Reddit. It looks more silly than anything to treat Reddit like Beetlejuice and not say its name.