Ask Me Anything AMA with Dr. Joe Pesce

[DrJoePesce]

If there was Water on mars how come the rovers have not found caves?

Thanks for the question.

To date, rovers have been sent to relatively bland (but still scientifically interesting) landscapes. Why? Because bland equals safe (to move around).

Caves have been seen from Mars orbit, however. Take a look here: https://www.space.com/mars-lava-tubes-radiation-safe.html and there is lots of water on Mars:. For example, https://www.space.com/mars-water-ice-map.html

 

[Amar Chavadannavar]

Respected Sir, Why is it Universe not even in every direction?

 

[Helio]

Thanks Dr. Pesce for hitting every pitch, and I think all are findable in the parking lot!

Do you have a favorite probe you pay more attention to than others? [Was it your advice that the solar Parker probe be launched at night? (one of my favorite jokes)]

 

[WGA]

is the smallest black hole ten miles wide or are there smaller black holes

 

[Indiangirl1966]

Hello Everyone.

I’m looking forward to this AMA and to hearing from you with your questions about astronomy! I will try to answer as many as possible.

I'm an astrophysicist primarily interested in the environments of the galaxies hosting supermassive black holes (also known as Active Galactic Nuclei). I've worked with clusters of galaxies, and the atmospheres of giant and supergiant stars. Currently I'm a Program Director at the National Science Foundation (NSF), Division of Astronomical Sciences, responsible for the National Radio Astronomy Observatory (NRAO); a part-time Professor at George Mason University in Fairfax, Virginia; and a Visiting Professor at the University of Colorado, Boulder, Colorado. And I'm a Fellow of the Royal Astronomical Society. Oh - and I LOVE all things Star Trek!!

I have a broad understanding of the field, but it’s vast (one could even say “astronomically” large), so I might need some time to find the answer.

Also, there may be lots of questions I can’t answer, because I don’t know – and maybe the answer isn’t yet known (that’s a fun part about astronomy – lots of unknowns still). Please keep this in mind.

Astronomy is exciting, and we live in an exciting time for the field. Thank you for letting me share it with all of you!

Dr Joe

welcome to the forums joe

 

[DrJoePesce]

welcome to the forums joe

Thank you! It's a pleasure being here with you.

 

[DrJoePesce]

Respected Sir, Why is it Universe not even in every direction?

Thanks for the question, Amar.

On the scale of galaxies and clusters of galaxies, there are differences depending where you look. The universe is clumpy on a zoomed-in scale: Here there are lots of galaxies, over there are big “holes”, or voids. Clusters of galaxies seem to be organized in very long filaments. But if you zoom out – this clumpiness is surprisingly uniform on the larger scales.

And, if we look at the Cosmic Microwave Background (CMB) radiation (the fossil radiation field from when the universe was very hot – now cooled down a couple of degrees above absolute zero), the universe is highly uniform – the same everywhere.

 

[Indiangirl1966]

early this morning I was out on my porch and saw a bright object in the western part of the sky,that was really bright,am not sure what I was looking at , it was bright and low in the sky,could have been Saturn or Mars that I might have been looking at?

 

[WGA]

if there was a black hole that ways as much as the sun how big would it be?

 

[DrJoePesce]

Thanks Dr. Pesce for hitting every pitch, and I think all are findable in the parking lot!

Do you have a favorite probe you pay more attention to than others? [Was it your advice that the solar Parker probe be launched at night? (one of my favorite jokes)]

I love them all! Cassini was great (and Huygens!); Voyager for their pluckiness; SOHO; the Mars rovers. What can I say?

 

[DrJoePesce]

is the smallest black hole ten miles wide or are there smaller black holes

Stellar-sized black holes – with say a mass of ~3 times that of the Sun, on the low end – indeed would have a diameter of about 10 miles (18km). It’s unlikely stellar-sized black holes have mass much lower than this.

Some models indicate that “atomic”-sized black holes could exist (or existed in the past): That is, they are about the size of an atom. These black holes have never (or not yet) been detected. If such black holes did form in the early universe, they probably would have evaporated by now (via Hawking radiation).

 

[Indiangirl1966]

would have been a Black hole that I saw cause I would love to
Study the object futher

 

[DrJoePesce]

if there was a black hole that ways as much as the sun how big would it be?

A black hole with the mass of the Sun (note, this is unlikely) would have a diameter of just under 4 miles (6km)

 

[DrJoePesce]

early this morning I was out on my porch and saw a bright object in the western part of the sky,that was really bright,am not sure what I was looking at , it was bright and low in the sky,could have been Saturn or Mars that I might have been looking at?

I can’t be entirely certain what you have seen, but assuming you are in the Northern Hemisphere, and it’s a planet, it could be Jupiter and Saturn (which are both in the SSW part of the sky in the early morning).

 

[Indiangirl1966]

I can’t be entirely certain what you have seen, but assuming you are in the Northern Hemisphere, and it’s a planet, it could be Jupiter and Saturn (which are both in the SSW part of the sky in the early morning).

I do live in the Northern hemisphere of the country
I want to be able to study whatever it was that I was seeing

 

[DrJoePesce]

I do live in the Northern hemisphere of the country
I want to be able to study whatever it was that I was seeing

Space.com has a nice night-sky round-up. Here it is for June: https://www.space.com/33974-best-night-sky-events.html

 

[sasan]

Thanks for answering our questions.
I had a few questions:
1. Can dark matter form planets and stars? If so can we even detect that or is it that dark matter does not interact with itself?
2. What is the center of a Neutron star like (at least in more widely accepted theories)?
3. Do neutron stars start as Magnetars and then slowly lose their magnetic field's immense strength?
4. Do you think Europa has life underneath its surface?

 

[Helmer]

Is it possible that there is variations in the density of the higgs field, resulting in fluctuations in the weight of mass depending on where in space the mass is?
If so, could this explain the deviations we observe and currently explain with dark matter?

 

[Tim_Myth]

Talking to an astrophysicist is one of the things on my bucket list, so thank you for making yourself available to us Plebs!

First question: When I see maps of the universe that show galactic clusters, I always wonder if they are adjusted for the travel time of the light. That is, when I'm shown a map that marks Andromeda, am I being shown where it was ~2.5 million years ago when the light in the picture left, or has it been adjusted for its expected present day position even though we won't know exactly where its at for another 2.5 million years?

Second: Current models of the Big Bang show a period of rapid inflation in the beginning. I'm assuming that only the lightest of elements appeared in the beginning since heavier elements are formed from the novas of stars. I'm also assuming that solar winds push lighter elements further and faster than heavier elements. Could this account for the rapid early expansion?

Lastly (since I see you have an interest in inter-species communications): Are you aware of any species that clearly communicate with another species? And I don't just mean parasitic communications where one species has learned danger is nearby when some other species makes a certain sound, nor do I mean people teaching sign language to one particular animal. I'm wondering if, for example, an ant can lay a trail that a beetle can follow and vice versa. Or maybe a dolphin is able to find a school of tuna thanks to a heads up from a pod of whales.

Again, thanks for taking the time to answer silly questions that I could probably answer for myself with a few minutes of googling.

 

[Indiangirl1966]

Space.com has a nice night-sky round-up. Here it is for June: https://www.space.com/33974-best-night-sky-events.html

IS it possible that I could have seen Neptune ?
I got the link to the star chart thank you

 

[DrJoePesce]

IS it possible that I could have seen Neptune ?
I got the link to the star chart thank you

You would need binoculars to see Neptune. It's not visible to the naked eye (and certainly not bright).

 

[WildSoftail]

Regarding the topic of how LIFE got started on earth:

Life on earth endured at least 5 extinction level events and bounced back each and every time, whether it be in the form of plants and grasses and primitive simple life in the seas or more complex life forms such as dinosaurs that dominated the planet for 100's of millions of years before being wiped out by a catastrophic impact by an asteroid or comet and even then life bounced back giving mammals there foot hold to evolve.

If other earth-like planets are found and somehow verified and if life is found to be common place among habital liquid water sustaining rocky worlds and if life basically forms in the same way through-out the cosmos as it did here on Earth.....

How plausible would it be to discover a world (an Earth II) where life did start much the same way as here at home. Where life followed the same evolutionary paths with lots of different circumstances and one of those circumstances being that no catastrophic collisions between that life bearing world and any cosmic debris took place and no catastrophic climate changes took place. Is it possible that dinosaurs could be the dominant form of life on another world?

 

[WGA]

I'm going to buy a new telescope. I have not used a telescope yet, but I what to see nebula, deep space objects and the closest superior planets in detail and my budget is about $500. What would you recommend? Refractory is my best bet, correct, but magnification and lens length would be a good choice? Thank you.

 

[WGA]

I was watching a show about the sun and it said the suns gravity extends for at least two light years. then I watched a different documentary and it said that the gravity of the sun extends for one light year. What is the truth behind this?

 

[WGA]

The biggest black hole I know of has 32000000000 (32 billion) soler masses. How far would the gravitational effect of it reach?