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Ask Me Anything AMA with Dr. Joe Pesce

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rod

Oct 22, 2019
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Helio, Dr Joe Pesce said "The longest baseline is Hawai’i to St. Croix, 8,600 km (5,350 miles), providing a resolution of 0.17 – 22 milliarcseconds (mas)."

That is almost impressive :) At 10 pc distance, 22 mas is about 0.22 AU diameter resolution or close to 24 solar diameter resolution. Helio, someday the radio telescope arrays and V-band equipment, may locate and image the 'Mandalorian home world'.
 
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WGA

Jun 24, 2020
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Hey WGA!

I haven’t seen what you did, so don’t know exactly what they are talking about, but 2 light years might be a clue. It could be they were talking about the gravitational influence of the Sun compared to the nearest star, the alpha Centauri system just over 4 light years away. If I’m floating in interstellar space and get close to the Sun, I will be attracted to it (and likewise if I’m close to alpha Centauri, I will be attracted to it). At a VERY general level, if I’m within about 2 light years of the Sun, it’s gravity will be win out over the alpha Cen system, and if I’m more than 2 light years from the Sun, alpha Cen’s gravity will win. This isn’t EXACTLY true because there are three stars in the alpha Centauri system, so it has more mass (and hence gravity) than the solar system does, so that maybe that’s where the one light year number comes from. I don’t know what the exact sphere of gravitational influence of the Sun is.

They might have been talking about something else, but I can’t know what! ☺

I should note: The force of gravity becomes weaker with distance very rapidly, but there is still a force, no matter how small. So, the Sun’s gravity extends everywhere, and affects objects in the center of our Milky Way, or in the Andromeda galaxy, or wherever in the universe – just at a minute level!
Thanks for your answer and I had no idea that the suns gravity extends that far thanks for the information :)
 
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Apr 2, 2020
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Nice meeting you, Dr Joe, here on Space.com! My question is do you consider that we are now in the age of RPA & Intelligent Automation that all things a are now possible especially in Astonomy?
 
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Jun 25, 2020
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I have a very crazy question, let's assume that there is a superficial being, totally unaffected by gravity in other words gravity doesn't work on him, he tries to go inside the event horizon of a black hole at a speed enough to break his bones, he's safe because he is totally unaffected by black hole's gravity (just an assumption). Now my question is will he crash and break his bones as he hits the infinitely dense region of space or will he just pass-through?
So far I knew that the higher the density of an object is, the stronger it is. I was wondering if it is same for black holes
 
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DrJoePesce

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Mar 31, 2020
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Great to hear! Do you have optimism for establishing radio telescopes (using interferometry, no doubt) on the "dark" side -- it kinda fits -- of the Moon before those optical folks take all the ice? ;)
This has been a topic of discussion for many decades (certainly my entire career and well before)! A radio instrument on the Moon would be interesting, not the least of which because on the far side, the interference from radio transmissions on Earth are blocked, so it is a much less noisy environment. Plus, the Moon is a nice, solid, platform (compared to a space-based observatory). And craters could be used as support structures for dishes. I don’t want to bet when it will happen, however!
 
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DrJoePesce

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Mar 31, 2020
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What's your favorite subject in astrophysicists

Hmm – the most difficult question of the week! I am interested in all aspects of the field. In general, I think the new findings being made because we are working in new frequency/wavebands and with new instruments are all fantastic – whatever the subject. Mysteries are great: Fast Radio Bursts, Dark Energy, Dark Matter, the big black holes and galaxies soon after the Big Bang, etc. New capabilities coming online: NSF’s DKIST solar telescope (https://www.nso.edu/telescopes/dki-solar-telescope/) and the NSF’s Rubin observatory (https://www.aura-astronomy.org/centers/nsfs-oir-lab/rubinobservatory/) will be game changing for the field. And, more specifically: certainly anything black-hole related, Active Galactic Nuclei, and exoplanets.
 
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DrJoePesce

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Mar 31, 2020
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Nice meeting you, Dr Joe, here on Space.com! My question is do you consider that we are now in the age of RPA & Intelligent Automation that all things a are now possible especially in Astonomy?
Thanks ImmortalMelvz. It's nice meeting you too!

AI, machine learning, and RPA will certainly play a large role in astronomy. The volume of data coming out of our observatories (currently, and even more so in the next couple of years at new generations of instruments and observatories come online), will require robust use of AI. For example, the data volume of NSF's Rubin Observatory (https://www.aura-astronomy.org/centers/nsfs-oir-lab/rubinobservatory/) will require robust AI.

By the way, if you are interested, here is some of what the NSF does in the AI realm: https://www.nsf.gov/cise/ai.jsp
 
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DrJoePesce

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Mar 31, 2020
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I have a very crazy question, let's assume that there is a superficial being, totally unaffected by gravity in other words gravity doesn't work on him, he tries to go inside the event horizon of a black hole at a speed enough to break his bones, he's safe because he is totally unaffected by black hole's gravity (just an assumption). Now my question is will he crash and break his bones as he hits the infinitely dense region of space or will he just pass-through?
So far I knew that the higher the density of an object is, the stronger it is. I was wondering if it is same for black holes
I’m afraid we can’t answer this question because our physical laws break down within the event horizon, so anything is possible, I guess. The extreme density of the singularity in a black hole is what causes the extreme gravitational field.
 
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DrJoePesce

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Mar 31, 2020
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We’ve had a great series of questions over the last couple of days!! I’d like to share with you another of our radio observatories, the Atacama Large Millimeter/submillimeter Array (ALMA; https://science.nrao.edu/facilities/alma) which we support as part of NSF’s National Radio Astronomy Observatory. This is a cutting-edge scientific facility, in the middle of the Atacama Desert in Chile, at more than five kilometers above sea level (so there is minimal water vapor in the atmosphere). This is a fabulous instrument making new and phenomenal observations, from solar-system objects to sources in the most distant past, and everything in between! Explore the website and let us know what you think!
 

rod

Oct 22, 2019
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Dr. Joe Pesce, what is the resolution of ALMA? I read various reports from ALMA indicating very detailed views in radio astronomy of dust disks seen around some stars, etc including accretion disk masses reported, something I like to follow. Yesterday you said another array showed resolution from 200 to 40 mas and another 22 mas or smaller. FYI, I link the two links you posted here--Rod
 
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Jun 26, 2020
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Hello Dr. Joe -

I am BRAND NEW to the community so imagine my delight in seeing this amazing feature allowing people like me to directly ask an expert a question. I’ve obviously found the right place to expand my knowledge! So here goes:

I’ve had this hypothesis on the inner planet creation for many years as I never bought into they just “naturally” formed when the gravity of the sun, even being new, would be too tremendous for small inner planets to form. The moons of Jupiter; however, seem to me to be perfect examples of planets forming just as they are by Saturn and Neptune, etc. Since we have observed gas giants near suns in other solar systems, wouldn’t a gas giant forming near the sun FIRST, which would then be torn apart by a growing sun capturing the moons to become inner planets make some sort of sense? What would you say is wrong with this idea and where perhaps I should focus my research in order to understand better?
 

DrJoePesce

Verified Expert
Mar 31, 2020
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Dr. Joe Pesce, what is the resolution of ALMA? I read various reports from ALMA indicating very detailed views in radio astronomy of dust disks seen around some stars, etc including accretion disk masses reported, something I like to follow. Yesterday you said another array showed resolution from 200 to 40 mas and another 22 mas or smaller. FYI, I link the two links you posted here--Rod
ALMA’s resolution is ~6 milliarcseconds as to 4.8 arcseconds (over frequency range and array separation). The reconfigurable array ranges from 150m to 16km.

You might be interested in the ALMA observations of circumstellar disks (dust around newly formed stars), with some of the gaps *probably* caused by newly formed planets: https://www.space.com/infant-stars-planet-forming-disks-images.html and https://www.space.com/37524-super-earth-planet-formation-puzzle.html

And even circumplanetary disks, where moons might be forming around the exoplanets: https://www.almaobservatory.org/en/press-releases/moon-forming-circumplanetary-disk-discovered-around-young-planet-in-distant-star-system/
 

DrJoePesce

Verified Expert
Mar 31, 2020
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I thought I saw a post asking about non-spinning black holes, but can't find it now! So here are some thoughts:

Non-spinning black holes are theoretical objects and are unlikely to be found in nature.
Maybe a non-spinning black hole could form from a non-rotating star, but probably they don’t exist either.

All stars (and gas clouds and galaxies) have some amount of rotation (angular momentum), and this is conserved when they collapse, so the black hole that forms from a collapsed star is going to be rotating rapidly.
 
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rod

Oct 22, 2019
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Hello Dr. Joe -

I am BRAND NEW to the community so imagine my delight in seeing this amazing feature allowing people like me to directly ask an expert a question. I’ve obviously found the right place to expand my knowledge! So here goes:

I’ve had this hypothesis on the inner planet creation for many years as I never bought into they just “naturally” formed when the gravity of the sun, even being new, would be too tremendous for small inner planets to form. The moons of Jupiter; however, seem to me to be perfect examples of planets forming just as they are by Saturn and Neptune, etc. Since we have observed gas giants near suns in other solar systems, wouldn’t a gas giant forming near the sun FIRST, which would then be torn apart by a growing sun capturing the moons to become inner planets make some sort of sense? What would you say is wrong with this idea and where perhaps I should focus my research in order to understand better?
Arctic Frost, I think you are asking the same in this thread too, https://forums.space.com/threads/the-creation-of-the-inner-planets.32173/

I was getting ready to post a note but will let Dr. Joe tackle now :)---Rod
 
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DrJoePesce

Verified Expert
Mar 31, 2020
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Hello Dr. Joe -

I am BRAND NEW to the community so imagine my delight in seeing this amazing feature allowing people like me to directly ask an expert a question. I’ve obviously found the right place to expand my knowledge! So here goes:

I’ve had this hypothesis on the inner planet creation for many years as I never bought into they just “naturally” formed when the gravity of the sun, even being new, would be too tremendous for small inner planets to form. The moons of Jupiter; however, seem to me to be perfect examples of planets forming just as they are by Saturn and Neptune, etc. Since we have observed gas giants near suns in other solar systems, wouldn’t a gas giant forming near the sun FIRST, which would then be torn apart by a growing sun capturing the moons to become inner planets make some sort of sense? What would you say is wrong with this idea and where perhaps I should focus my research in order to understand better?
Welcome ArcticFrost! I hope my reponse isn’t disappointing!

This is way outside my area of expertise, but here are some thoughts.

When I was growing up as a professional astrophysicist, eons ago, the model for our solar system seemed to be quite robust and all was well in the land of planetary dynamics: The circumstellar disk from which the planets formed (see my response to a previous poster) started out with dust and ice, the disk nearer the newly forming Sun gets heated and that drives away water and light elements, leaving only material from which rocky planets could form. Farther out, it’s colder and ices and light elements remain, forming the gas giants. This was a nice, consistent, and logical picture that remained for many decades…. Until we started finding exoplanets, and in particular gas giants very near their stars….And things became complicated.

Since these observations, all sorts of models have been generated to explain what we see around other stars (and to explain how our solar system formed).

Perhaps you are right.

But some other things to think about: As those large gas planets move around in their solar system (as we think Jupiter and Saturn may have), they could also have changed the orbits of smaller, rocky, planets (maybe even bringing them from the outer parts of the solar system to where they are now). Again, I’m not an expert but there are lots of resources out there now that we know about all sorts of different planetary systems. I encourage you to keep thinking about these things!
 
Jun 26, 2020
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rod

Oct 22, 2019
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1,060
Welcome ArcticFrost! I hope my reponse isn’t disappointing!

This is way outside my area of expertise, but here are some thoughts.

When I was growing up as a professional astrophysicist, eons ago, the model for our solar system seemed to be quite robust and all was well in the land of planetary dynamics: The circumstellar disk from which the planets formed (see my response to a previous poster) started out with dust and ice, the disk nearer the newly forming Sun gets heated and that drives away water and light elements, leaving only material from which rocky planets could form. Farther out, it’s colder and ices and light elements remain, forming the gas giants. This was a nice, consistent, and logical picture that remained for many decades…. Until we started finding exoplanets, and in particular gas giants very near their stars….And things became complicated.

Since these observations, all sorts of models have been generated to explain what we see around other stars (and to explain how our solar system formed).

Perhaps you are right.

But some other things to think about: As those large gas planets move around in their solar system (as we think Jupiter and Saturn may have), they could also have changed the orbits of smaller, rocky, planets (maybe even bringing them from the outer parts of the solar system to where they are now). Again, I’m not an expert but there are lots of resources out there now that we know about all sorts of different planetary systems. I encourage you to keep thinking about these things!
Arctic Frost and Dr Joe Pesce, I like the thinking here and answers by the pro :) Here are two exoplanet sites I use regularly that both of you may enjoy or already know about. http://exoplanet.eu/, currently 4280 confirmed and I did a MS SQL query. 3514 show periods <= 365 days so they orbit mostly where Earth is or closer and many have larger masses too, the average is 2.54 Jupiter masses. The other site I use is here, https://exoplanetarchive.ipac.caltech.edu/index.html. This site shows 4171 confirmed and my query shows 3592 listed with orbital periods less than or equal to Earth. Average mass is 1.32 Jupiter masses. Modeling the amount of protoplanetary disk material in our early solar system about 1 AU or less from the Sun and comparing with other exoplanets now - is very interesting and fun :)---Rod
 
Jun 26, 2020
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Welcome ArcticFrost! I hope my reponse isn’t disappointing!

Perhaps you are right.

But some other things to think about: As those large gas planets move around in their solar system (as we think Jupiter and Saturn may have), they could also have changed the orbits of smaller, rocky, planets (maybe even bringing them from the outer parts of the solar system to where they are now). Again, I’m not an expert but there are lots of resources out there now that we know about all sorts of different planetary systems. I encourage you to keep thinking about these things!
Thank you SO MUCH! What a wonderful reply that gives me so many avenues to turn my focus towards. I see that it would be wise for me to learn more about gas giants, their gravities and their influences. I have more focused on the sun’s dynamics even though there I have tons to learn as well.

This may tickle you, but I’m as giddy as a groupie meeting her first rockstar. Thank you so much for taking the time to educate us.

ROD - Thank you! You’re the coolest!
 
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DrJoePesce

Verified Expert
Mar 31, 2020
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Thank you SO MUCH! What a wonderful reply that gives me so many avenues to turn my focus towards. I see that it would be wise for me to learn more about gas giants, their gravities and their influences. I have more focused on the sun’s dynamics even though there I have tons to learn as well.

This may tickle you, but I’m as giddy as a groupie meeting her first rockstar. Thank you so much for taking the time to educate us.

ROD - Thank you! You’re the coolest!
Keep up the excitement and enthusiasm - that's what it's all about! :)
 
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