Well, it's 4pm March 21, and I'm going to stop taking questions for now. This was a lot of fun and great questions! I hope everyone enjoyed this AMA! If you want to know how we are doing with digitizing astronomical photographic plates, go to the Astronomy Legacy Project http://www.pari.edu/apda/alp

I've had 2 postdoc positions over a 7 year period, followed by 10 years as tenured Associate Professor in a Physics and Astronomy Department at a small university, and then in 2001 I left that position to become the Science Director at the Pisgah Astronomical Research Institute (PARI: http://www.pari.edu) where I currently work. PARI is a non-profit optical and radio telescope observatory and science education center located at a former NASA Tracking station in the U.S. in western North Carolina near Asheville.

As an astronomer for the past 30+ years, I have seen technological advances in astronomical telescopes and instrumentation that sometimes seems like they are out of some science fiction novel. Just take a look at today’s space- and ground-based telescopes that are making remarkable discoveries.

Every technological advance has led to new discoveries. What I find most interesting are the petabytes of data sitting in analog form from the late 19th century and early 20th century with untapped potential for even more discoveries. The data is in the form of photographic plates and films – digitizing these brings 20th century data into the 21st century digital world and all of its tools for data analysis. I am part of the Astronomy Legacy Project (http://www.pari.edu/apda/alp) team dedicated to digitizing the plates and films. We do have a crowdfunding campaign going (http://www.indiegogo.com/projects/astronomy-legacy-project/) for equipment to digitize that analog data.

So, I’m going back to my roots where as a new astronomer 30 years ago I was using photographic plates. Later I joined in the astronomical community frenzy for CCD cameras in the late 1980’s and early 1990’s that have become the mainstay tool of observational astronomers today. I’ve seen a lot of changes in the ways astronomers make their observations. I would be happy to reply to questions about changes in astronomy from the late 20th century to the present. So, ask me anything!

Proof: http://i.imgur.com/S5th3QS.jpg https://www.facebook.com/mcastelaz

Comments: 100 • Responses: 46  • Date: 

12ealdeal5 karma


mcastelaz6 karma

It's always fun to anticipate what the next great leap in technology will be and how it will be used by astronomers. In the 1980's I think the big thing was the advent of electronic cameras. There were a lot of questions about the ability to use them with telescopes and get good calibrated data. So, I did begin imagine their use, but never did expect to see the extent to which they dominate the field today.

30 years ago I observed infrared reflection nebulae - the cocoons of newly formed stars. This was really cool - imagine a star only 10,000 years old! Today I find the discovery of planets around other stars to be really cool.

MrsDucky4 karma

I just want to thank you for the awesome work all of you at PARI are doing. It's one of my favorite places in NC; I did after all get married on the site.

mcastelaz3 karma

We all remember your wedding here! Thanks for the encouraging words!

originalturtle3 karma

Thanks so much for your great work, I have a nerd question for you sir: Hawking says (Brief History of Time) the sum of all energy in the universe is zero. The negative gravitational energy cancels out the positive energy represented by matter. He accounts for everything. This is also a key component to inflationary big bang theory of course. Yet Neil Degrasse Tyson says 85% of the gravity in the universe is unaccounted for, IE dark matter and dark energy. (Bill Moyer Interview last month) Is this contradictory, updated information or am I misunderstanding something?

mcastelaz5 karma

I'm not I know enough about this to answer your question. But, it sounds like Dr. Degrasse Tyson might be talking about the largest components of our universe being dark matter and dark energy, and matter makes up a very small percentage. So, when you see stars, planets, nebula and galaxies, you are seeing only about 4% of the universe! There is a lot we don't see because it is in the form of dark energy and dark matter. I'm hoping some young scholar will one day figure out a way to "see" dark matter and dark energy!

originalturtle3 karma

Thanks again! My favorite dark matter theory so far was from a kid actually, 10 years old.

"It's probably just a bunch of rocks"

I laughed hard, then realized he could be correct.

mcastelaz1 karma

I agree. We've talked about dark matter as rocks as well. Sometimes the simple answer is the best

Twinkie_Zombie3 karma


mcastelaz8 karma

It's the Complete Idiots Guide to Javascript

GiovanniMoffs3 karma

Would you prefer to be called a skientist?

mcastelaz3 karma

I haven't heard of that one before. I like "astronomer".

Tactimon3 karma

When you stare into the abyss, does it actually stare back at you, or not so much?

mcastelaz3 karma

Every image we take of objects in space tell us a story. So, it's not really staring back, as much as giving us an idea of our place in this universe.

Comrade633 karma

Stupid question, but of all of the thirty plus years you have been an astronomer, have you seen any indication of other life forms in space other than us?

mcastelaz7 karma

No. I don't know of anyone who has. But, if there is, I would suspect we'd find life either on Titan or Europa. NASA has a plan to send a robotic mission to Europa.

origiins2 karma

How long would that take?

mcastelaz3 karma

I think maybe in the next 10-20 years - depending on funding. It may even be done by a private space company.

InterplanetaryFlight3 karma

Hello Dr. Castelaz,

I know we can visualize gravity of objects in space similarly to this: (http://upload.wikimedia.org/wikipedia/commons/d/d1/GPB_circling_earth.jpg).

But how would we visualize gravity when it comes to the scale of a galaxy? Does the visualization of gravity react the same way as it would with Earth as it does with a galaxy? With all the mass in a galaxy, I wonder if it all would become collective and form a global pool of mass? If not, what defines the mass of a galaxy?

Probably a stupid question.

mcastelaz2 karma

I think the same visualization holds for the galaxy, if you think on a larger scale, as though the galaxy were a point source. But, the gravitational field would look much more complicated if we zoom into a spiral arm for example. Each star in a spiral arm would have its own field add up with fields from other stars. This is a very good question and probably could use some supercomputer time to simulate!

steveo7572 karma

Do you believe there is extraterrestrial life out there somewhere? If so, when do you think we will have definite proof of it?

mcastelaz3 karma

Yes. I think the universe was made for life. When we fly to Europa or Titan and take a close look we may very well find life.

heykatieben2 karma

Hi Mr. Castelaz!! :) So cool to see you here! :) This is Katie, Anna and I were friends in high school. I've lost touch with her, can you send me her email or tell her Katie Benedetto would love to hear from her? I'm [email protected] and on Facebook (Katie Benedetto Jones). Thank you! :)

YAY, I'm excited to read this AMA and learn what you do! :) :) It's so good to see you here!! :)

mcastelaz2 karma

Hi Katie! I'll pass your message on to Anna. Great to hear from you!

Vizen1 karma

Hi, simple question that might be a little off topic; what is it about the big bang theory that makes it such a good theory compared to others such as quasi steady state?

mcastelaz2 karma

The cosmic background radiation is difficult to explain with a steady state model, but easy to explain with the big bang model. Perhaps some young scholar is growing up today who may bring the steady state model back.

vicorator1 karma

Hi! As a young space enthusiast I would love to work in Astronomy or Astrophysics one day. I just want to ask you what your childhood was like and why did you become a Astronomer. Also if you have on, what is your favorite star?

mcastelaz1 karma

Hi! I grew up in a city, but still was able to observe Saturn, the Moon, and other bright objects with my 2-inch refractor. I remember being very excited seeing those objects and begin to wonder about space in general. I grew up in the 60's during the space race and watched every Mercury, Gemini, and Apollo mission. Along the same lines, I also liked to build and launch rockets, mess around with electronics and just build things. Becoming an astronomer just seemed like a natural thing to do.

My favorite star is GSS30 in the constellation Ophiuchus - but it can only be seen in the infrared part of the spectrum. My favorite nebula is the Orion Nebula.

Vertskater1011 karma

Hello! Im very interested in being an astronomer. Im majoring in physics right now planning on going into astrophysics. What was the first thing that turned you onto astronomy? And fun fact my mother is dating Josh Freeman from the dark matter survey

mcastelaz2 karma

Congrats on being a physics major! I've been interested in being an astronomer since I can remember. I think getting my first telescope was the clincher.

fyen1 karma

Do astronomers (not mixed professions like astrophysics) use tools or sources of information not directly related to their field of work other than all kinds of telescopes? For example, running experiments on a particle collider or gathering samples somewhere on earth, etc?

mcastelaz3 karma

There are number of different tools: like IceCube, a neutrino detector, and supercomputers to do simulations of galaxy collisions, for example, or high energy work at places like Oak Ridge where conditions like those of supernovae are studied. There are also gravitational wave studies using instruments like the Laser Interferometer Gravitational-Wave Observatory (LIGO). So, astronomers do go to labs and computing facilities where they can develop their models and ideas of what they have observed.

ConSarn1 karma

Some people think astronomy isn't practical so isn't worth the money. What would you say is the best reason why the country should spend money on astronomy?

mcastelaz1 karma

I'm biased. I think funding should be doubled. This would greatly increase our nation's intellectual capital.

hooshtin1 karma

Can you recommend a good telescope for me? I'm a novice, but I want to make astronomy a hobby. I want to learn more about what my eyes can't see.

mcastelaz1 karma

If you want something portable or easy to set up, then I would go with a 4 or 6 inch type of telescope. There are websites that sell just telescopes and accessories. If you want something that you can attache a camera to, then a larger 8 or 10 inch telescope would be good.
If there is a local astronomy club, they are always excited to help out.

UpVotesAllButTrolls1 karma

Is light pollution a problem for you the way it is for amateurs like me, or is the technology so much better at the professional level?

mcastelaz2 karma

Yes, light pollution affects us all the same way. Technology to limit light pollution would be best.

ConSarn1 karma

Do you have a favorite astronomer? Historical and deceased, I mean!

mcastelaz2 karma

Carl Sagan is one of my most favorite astronomers - he had an excellent ability to relate our work to the general public. Also, I'd like to add Jocelyn Bell Burnell who discovered the first pulsars, and Elizabeth Griffin who is a primary driving force in digitizing astronomical photographic plates.

mcastelaz2 karma

Oh - I forgot to mention I also like Brad Schafer who does excellent work on studying novae and transient phenomena.

belter21 karma

Is Daylight Saving Time a good idea or not?

mcastelaz2 karma

I don't know - personally I like Standard time. Anyway, astronomers use Universal Time for our observations.

sarahstrattera1 karma

Are you watching the new 'Cosmos'? Do you love it?

mcastelaz2 karma

Yes. I do like it. I think the explanations are very good - I especially liked the episode with explanations of DNA. The animations were fun to watch. Maybe a few scenes are a bit overdone, but science is so cool that that is easy to do.

gelroy1 karma

Does PARI do something like a weekly astronomy radio spot on some local stations?

mcastelaz1 karma

No, we don't - but that's a good idea! We do have a facebook page - https://www.facebook.com/Pisgah.Astronomical.Research.Institute and the Astronomy Legacy Project also has one - https://www.facebook.com/AstronomyLegacyProject PARI is open to the public 9-4 M-F, and on the second Friday of each month we have Evening at PARI starting at 7 pm with a guest speaker, then a tour, then a star party.

SpanktheBunny1 karma

When looking at the night sky, can we see any stars outside of our galaxy?

mcastelaz1 karma

On a good dark night, you can see the Magellanic clouds in the southern hemisphere, and the Andromeda Galaxy in the northern hemisphere. But, you can't see individual stars, unless a supernova were to go off in any of these galaxies.

Rabujan1 karma

If you could go to any planet what would that be?

mcastelaz1 karma

Venus - but I wouldn't care to stand on the surface. I think I would like to inhabit a spacecraft that floats in the atmosphere of Venus at just the right altitude where temperature and pressure are similar to Earth's (except I'd have to bring my own air). I think Venus us a very dynamic planet and would be exciting to explore. My favorite moon is Titan - it has methane lakes and atmosphere, although very different from earth.

Rabujan1 karma

Stupid Question but if someone actually landed on Titan wouldnt the methane lakes burn? I know that fire needs oxigen but space ships burn fuel in space. How? Turned out to be 2 questions.

mcastelaz1 karma

The reaction between elements in the rocket fuel cause the burn. I don't think the methane on Titan would be set on fire since the atmosphere of Titan wouldn't support the fire. Good question though - I wonder if there are volcanoes on Titan?

studentech1 karma

Hi Dr. Castelaz, thank you for your time today.

Two quick questions;

  • Do you still find time to do some observing in your down time? or do you find that observing has become a job that should stay at work?

  • If so, what does your personal collection look like, do you have any favourites?

mcastelaz1 karma

I'm more in a management position these days. PARO has a 0.4-m telescope and I have managed to observe V523 Cas, an eclipsing binary with a 5.5 hour period. I observed it in 2012 and 2013, and am writing a paper about the this star system. BUt, that' about all I have time for. I do spend more time teaching high school and college students how to use astronomical instrumentation, and they observe.

One of my favorite set of observations was a period in the late 1990's when I was taking time series spectra of Mira variable - stars that pulsate over a period of about 300 days. I also enjoyed tremendously making infrared observation in the early 1908's - it was cutting edge then.

So, my personal collection consists mostly of photometry and spectra.

Mankers1 karma

Mike, what would happen if we (the astronauts) send a mirrior into outerspace? would we be able to see it from earth?

mcastelaz2 karma

I think there are mirrors on the moon for laser experiments. Pretty cool.

n_mcrae_19821 karma

Might seem silly but did you have any thoughts on the "demotion" of Pluto to the status of "dwarf planet"? (It was on my mind, given the recent discovery that Pluto may in fact be bigger than Eris).

mcastelaz1 karma

I grew up with Pluto as a planet. But, there are dozens of large minor planets in the same vicinity as Pluto. As Dr. DeGrasse Tyson puts it, Pluto as the first of a new class of minor planet - quite an honor.

noott1 karma

Do you think crowd funding is the way for the future? It feels like Congress has been cutting so much funding from the NSF and NASA that grants have become increasingly difficult to obtain.

That being said, is there anything we can do to to convince them the importance of funding astronomy?

mcastelaz1 karma

Crowdfunding is still relatively new, so it's hard to tell what it's impact is. NSF and NASA award between 10% and 15% of all grant proposals submitted. This leaves a lot of very important and imaginative work unfunded, with money going to a very few. The rest of the researchers then must be funded either by private funders or foundations or crowdfunding if they want to do their work. Researchers like me are very grateful for that kind of support!

We are going the crowdfunding route for our Astronomy Legacy Project and have found so far that there are a lot of people who have not heard of the project or PARI become aware of what we are trying to do. That recognition, in addition to the donations, I think is important.

Kwiatkowski1 karma

Cool, I have talked a bit with one someone from there (don't want to say the name here but he's a friend of the guy at Blimpworks) about beefing up the renewable energy systems you have, especially wind. Unfortunately for you guys you live in a wind power dead zone. But hey, you have a decent solar recource to go off of so that's nice.

mcastelaz1 karma

We have two wind generators (900 W each) going. They seem to keep the batteries charged.

outrageousbog1 karma

Have you ever made a huge discovery that was published in the media ?

mcastelaz1 karma

I've had a few small newspaper and magazine articles. But, I think that the work we are embarking on digitizing 120 year old astronomical photographic plates is going to give us and many other astronomers a new data mine and we should anticipate some pretty awesome discoveries. 21st image processing technology is impressive and I can't wait to see what happens when we apply this technology to the high quality images taken by scientists before us.

urgehal6661 karma

Hi! Can you help me with my astronomy homework? I'm really struggling with the math aspect.

mcastelaz1 karma

Hmmm. What level of math? Is this algebra, trig?

Parzival_Watts1 karma

What's the most beautiful thing you've seen in the sky?

mcastelaz3 karma

My favorite object has always been the Orion Nebula. It is the home of new stars, molecular clouds, and bright nebulae. On a good clear night take a look with binoculars

Skeeders1 karma

The star Betelgeuse has always fascinated me since my father taught me a bit about it. Is it true that the star has already gone supernova and we are just waiting for the light from it happening to reach us? If so, how likely are our chances of seeing happen in our lifetime (I'm 29)?. What would it be like to experience seeing it go supernova?

mcastelaz1 karma

This would be a wonderful sight! The star is about 700 light years away, which is good because a supernova needs to be within 50 light years for it to harm us. Astronomers think that we have about 1,000,000 years before it goes supernova, based on its current state in its life cycle.

Betty_Felon1 karma

Are you guys hiring? I have an undergraduate in Physics, with Astronomy research experience, and soon to have a PhD in STEM Ed. ;)

mcastelaz1 karma

Hi. There is such an overwhelming need for STEM educators like you. As a non-profit we live off of grants and a few benefactors and we just don't have the funding right now. Send me your resume though - we are always writing proposals for grants and maybe something will turn up.

The_13_Snakes1 karma

What turned you towards astronomy? Were you an amateur astronomer as a kid?

mcastelaz6 karma

I have always been interested in astronomy. I got my first telescope when I was about 11 years old - I had to shovel a lot of snow to earn the money buy it. I didn't realize that I would one day be working with a 4-m telescope at Cerro Tololo Interamercan Observatory, or on Mauna Kea, or even today at PARI with two 26-m radio telescopes.

isoplex1 karma

Whats the one thing you regret of all this years as an astronomer?

mcastelaz1 karma

I wish I could do more - I'd like to fly in space, work closely on some of the robotoic mission to the outer planets, or help build some of today's most fantastic telescopes.

jcastelaz1 karma

What's the most interesting part of being an astronomer that you didn't anticipate at all when you started your career?

mcastelaz2 karma

I find the times I have spent with undergraduate interns teaching them how to do research was one thing I didn't anticipate. One of my favorite interns from 2002 has actually started his own company that is closely connected to green energy.

bufkinfinity1 karma

Is there anything you would like to see that you have never seen before?

mcastelaz4 karma

I would really like to see a supernova in our Galaxy! That would be a fantastic sight.

Will_Beau1 karma

Hi, Dr. Castelaz. It was interesting to read in the Concordia article yesterday that the photographic plates vary in size and even shape. I would assume magnification, also. In the Astronomy Legacy Project, will it be possible to provide size scales so that different images can be sized to correspond to each other (star to star)? Were astronomers "back in the day" thinking ahead to when people might compare side by side plates from different sources and provided some reference marks like scales?

mcastelaz2 karma

Astronomers were very careful to record the characteristics of the telescopes that they were using. So, thanks to their records, we know the plate scales and can easily compare one plate from telescope to a plate from another telescope. But, until we digitize the images, comparing plates side by side is very difficult to do. The images can be easily manipulated and compared when they are digitized. So,you have hit on a very important aspect of the whole digitization process!

toxxx1 karma

What are your favorite Sci-fi movies?

mcastelaz3 karma

The Star Trek movies of course are definitely among my favorites. The Babylon 5 seriies, and 2001 A Space Oddessy

Will_Beau1 karma

Is it possible to get measurements of luminosity from glass plates (and their scanned images)?

mcastelaz2 karma

Yes. But, we have to be careful to have enough dynamic range in the electronic camera that does the digitizing, and balancing the light table intensity and exposure time so we don't saturate the digitized image..

shawaddywaddy1 karma

What do you think the future of amateur astronomy will be like in 10-20 with technological advances?

mcastelaz2 karma

I think amateur astronomers, and professionals for that matter, will always enjoy looking through the eyepiece of a telescope. Beyond that, it may happen that amateurs will someday develop the capability to launch their own telescopes into space on CubeSats or another type of micro-satellite. That would be awesome!

shawaddywaddy1 karma

That sounds awesome. I'm also curious how familiar you are with Sir Patrick Moore? He inspired so many people in the UK to take it up as a hobby.

mcastelaz3 karma

Yes. He has several books, some of which I read as a kid. I think he was also inspiration here as well. He is dearly missed.