Samuel Jackson
I am a PhD student at The Open University, studying the brightness variations of Near-Earth Asteroids to help determine their surface properties.
Location Milton Keynes, United Kingdom
Activity
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@LeslyeSlater I'm currently the primary user of PIRATE working towards introducing new capabilities for it (asteroid tracking), and am involved with the maintenance and general operations of the telescope. :)
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We have a scheduler where people submit their observations. Depending on user priority, availability of the target, and other factors the scheduler works out which observations to submit to the telescope each night.
For students in certain modules (e.g. SXPS288 at the OU) it is as simple as logging on to a website where they can take control of the...
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Samuel Jackson replied to Susanne Frenzel
Quite possibly! From a philisophical standpoint I prefer this one as it would provide a mechanism for the start of the big bang!
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Samuel Jackson replied to Maureen Bowler
@PadraicMoran It does pose a unique problem for us all. It will be interesting to see how/if we manage to work with industry to mitigate these problems.
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Samuel Jackson replied to Alan Thomas
@PadraicMoran Unfortunately these things happen in old age ;)
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Samuel Jackson replied to Keith Pearson
That is one of the goals of JWST! See more here:
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In order to get accurate measurements we require errors of around 0.1% or less. Hence high precision techniques and instruments are required!
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Samuel Jackson replied to Anna Safon
I certainly catch myself spiralling into a philosophical black hole often. Then I just have to remind myself of all the work I have to complete by the end of the week and suddenly the problems of the universe become a secondary consideration again. :')
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Unfortunately I fear we will be the hostile ones in any encounter.
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There is some good discussion about that question here:
https://physics.stackexchange.com/questions/141875/how-do-you-estimate-the-mass-of-a-star
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Samuel Jackson replied to Alyson Kelman
I sincerely hope that things improve for all of you suffering with the fires.
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We don't assume that it can only form in this way, however due to it only being observed to form this way so far it makes sense to divert our limited resources to areas we know that life will likely form rather than speculative observations of all types of systems.
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Samuel Jackson replied to Helen B
In fact a new method was recently used by researchers at the OU to detect three new exoplanets! More information here:
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It certainly gets tested regularly! A lot of caffeinated drinks helps soothe the mind enough to deal with it however! ;)
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Samuel Jackson replied to Helen B
It definitely should be visible by the naked eye. Unfortunately I doubt any amateur telescopes would be able to pick out any detail like the large professional telescopes can.
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Unfortunately we can't do this in a lab on Earth as the gravitational field of the Earth would interfere with the dynamics of the cloud collapse!
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Samuel Jackson replied to Leslye Slater
@LeslyeSlater I'm not entirely sure, however my assumption would be that the death of the star would be energetic enough to remove the outer planets from the system (either by destruction or their loss from the system due to the lower mass of the star as you suggest).
I certainly wouldn't expect to see planets left in these systems!
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Samuel Jackson replied to Carol Cooper
The interpretation posted by @İbrahimAtakanKubilay is correct. See my comment here for further explanation:
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Samuel Jackson replied to Leslye Slater
It's perfectly reasonable to assume that other life may be able to form and thrive in different environments. However, due to the limitations of where life can form on Earth being our only example it makes sense to restrict our current searches (which have very limited resources) to those areas we know will likely contain life rather than speculating where...
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ARROW is available to use in some of our undergraduate modules (e.g. SXPS288):
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Samuel Jackson replied to Karen Wells
@HelenB Unfortunately we know next to nothing about their surfaces, we just have to speculate based on what we think the conditions would be like on the planet.
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This forum discussion helps break things down to hopefully answer your question:
https://www.physicsforums.com/threads/why-does-a-gas-cloud-spontanously-rotate.93098/
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Samuel Jackson replied to Maureen Bowler
@StephenHowells The area it is being put in is not a standard orbit (it will be located in what we call L2) which is an unstable orbit anyway (requires fuel to keep it there). This means that eventually JWST will drift away from other objects located there.
Unfortunately throwing them into the Sun would require so much extra fuel that the original mission...
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Samuel Jackson replied to Freek B
@LeslyeSlater The latter, it must have formed after enough supernovae events in order to contain the required concentrations of heavy elements as you suggest. :)
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Samuel Jackson replied to Karen Wells
They are artists impressions of what they may look like based on their observed properties (distance from their star, etc).
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Samuel Jackson replied to Margriet Hofman
We commonly think of asteroids of being made up of rocky materials and metals, whereas comets are thought to be mainly made up of ice and rocky material. We don't commonly see ices in asteroids.
However, the lines drawn between the two are becoming increasingly blurred with more observations (e.g. 'Active Asteroids').
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Samuel Jackson replied to Tom Dussman
The one I was taught was 'My Very Easy Mnemonic Just Speeds Up Naming (Planets)', however younger me did not like the confusion that 'Mnemonic' causes - stupid silent letters. :)
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Samuel Jackson replied to Margriet Hofman
This table may help approximately illustrate some of the timescales involved:
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Samuel Jackson replied to Tom Dussman
From what I know about asteroids I can tell you that almost all asteroids are irregularly shaped, however Ceres is rounded and that is around 1000km in diameter. The answer lies within the concept of 'Hydrostatic Equilibrium' which is too complex to go into detail here, however I encourage further reading if you're interested! :)
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They can form in various inclinations. For example, the planetary disk of the Sun is inclined around 60 degrees to the galactic plane.
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Samuel Jackson replied to Richard Torpey
Yes that's correct.
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Samuel Jackson replied to Karen Wells
Tripods certainly help massively (just not if they're from 'the war of the worlds')!
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Samuel Jackson replied to Helen B
Some astronomers spend their entire careers studying dust!
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Samuel Jackson replied to Tom Dussman
Then spread that out over the number of star systems that are out there and that probability starts to become more palatable. The universe is a horrendously large place. :)
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There are gravitational interactions between different galaxies.
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Samuel Jackson replied to Judith Ballard
Billions of billions of years, so no need to worry about it quite yet! :)
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Samuel Jackson replied to Carol Cooper
Yes it will essentially be too far spread out due to the expansion of the universe to allow new stars to form.
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Samuel Jackson replied to Helen Smith
The three spatial dimensions aren't the only dimensions in our Universe, however. Time is the fourth dimension in our universe! :)
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Samuel Jackson replied to Maxi Weigert
@PadraicMoran From what I can find online it appears to be credited to Roger Cotes in 1714!
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Samuel Jackson replied to Mic Laird
@MicLaird Any dust near enough to get heated up enough to observe this excess would have to be in orbit due to proximity.
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Samuel Jackson made a comment
Very happy to see so many people have enjoyed the course! Well done to everyone for engaging with the course so much. Many questions posed by you all have helped me broaden my own understanding in the process of finding the answers and articles you seek!
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Samuel Jackson made a comment
Reminds me of one of my favourite quotes:
“Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying.”
― Arthur C. Clarke
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@MicLaird I think this calls for a FutureLearn course on bees!
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Samuel Jackson replied to Mic Laird
From the spectrum we observe an Infrared excess meaning that the dust is being heated up. If the dust was just between us and the star we wouldn't expect to see this heating.
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Yes these observations take place over many years!
It is a difficult challenge to disentangle all of the planets in a system creating these dips but it is possible to pick out the individual periodicity of them.
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Samuel Jackson replied to Pete B
Unfortunately I can't help too much with external links. However for the papers linked on the website a good resource to find them is 'google scholar' or 'NASA ADS'.
Most of the links appear to be working for me though.
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Samuel Jackson replied to Jeff Morgan
Unfortunately the resolution required for that isn't possible just yet, but who knows maybe in 10-20 years time!
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Samuel Jackson replied to Jeff Morgan
We have only detected two interstellar objects so far, mostly due to the limited time they spend in the solar system and that fact that they are unlikely to come close enough to the star to be sufficiently illuminated to observe them.
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Samuel Jackson replied to Jeff Morgan
There are many theories regarding the formation of the planets and why they are in their current observed positions. One such model is the 'Nice Model' and is too complex to explain in a comment so encourage further reading if you are interested! :)
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Samuel Jackson replied to Alan Thomas
Indeed this is an image in infrared!
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Samuel Jackson replied to Doug Karo
On the order of millions of years, but yes still relatively early in the lifetime of a star.
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Samuel Jackson replied to Philip Keith
The age of Rigel is estimated at around 8 million years.
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Samuel Jackson replied to Helen B
Proxima Centauri has been observed to have a rocky planet potentially within the habitable zone (Proxima Centauri b)
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Samuel Jackson replied to Cindy Belt
Our Sun is a 'metal-rich' star meaning that it falls within the 'Population I' category (with 'Population III' stars confusingly being the earlier metal-poor stars).
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Samuel Jackson replied to Richard Pacific
Referring to my recent comment on your other comment regarding black holes (https://www.futurelearn.com/comments/36527662), as the other stars in Orion are not gravitationally bound the black hole would not absorb the other stars in Orion (they are all quite far away from eachother).
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Samuel Jackson replied to Andy Becker
@MelanieMonteith Black holes do not 'suck' material. They just have a graviational force that is so great after a point that light can't escape. You can even orbit a black hole (our galaxy is orbiting a supermassive black hole at the centre). The only way another star or planet will be absorbed by a black hole is if it enters the region of gravitational...
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Samuel Jackson replied to Tom Dussman
@MelanieMonteith I shamelessly steal the following explanation from a page containing a much more mathematical approach:
"Virtual particle pairs are constantly being created near the horizon of the black hole, as they are everywhere. Normally, they are created as a particle-antiparticle pair and they quickly annihilate each other. But near the horizon of...
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Samuel Jackson replied to JAIME HERRERA FARIA
@MelanieMonteith Disappointingly the answer is currently "we don't know". The conditions present at the big bang are unknown as we can't see anything before the big bang or even very close to it (furthest back we can see is the Cosmic Microwave Background - ~380,000 years after the big bang).
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Spiral galaxies may have had interactions with smaller galaxies, for example the Mily Way is currently absorbing a much smaller galaxy. However any large scale interactions will cause this disruption and disorder.
I am unsure of proportions, however I would estimate that most galaxies within galaxy clusters will eventually have some sort of large scale merger.
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Samuel Jackson replied to Doug Karo
@DougKaro That is certainly a factor as well, there will be an overall decrease in matter further out regardless.
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Samuel Jackson replied to Doug Karo
It will certainly be interesting to see how this correlates with observations. Any modification to General Relativity will have to be able to carry the same observational weight as the original theory!
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Samuel Jackson replied to David Brown
@DavidBrown Don't worry I wasn't either but I'm sure we'll have our own events to look forward to!
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Samuel Jackson replied to Pete B
Yes the image is not a true representation of the distance between objects in the asteroid belt, but neither is it an accurate representation of the distances between planets compared to their sizes! If we wanted accurate representations we wouldn't be able to see anything in the image. ;)
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Samuel Jackson made a comment
A useful article for those that would like further explanation:
https://www.scientificamerican.com/article/how-is-a-star-born/
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Samuel Jackson replied to Pete B
However, it does still provide a useful tool for constraining our search for those areas most likely to be unaffected by things like supernovae. With limited telescope time available, we must all try to find the best locations to search before submitting observing proposals otherwise we'll be laughed out of the door. ;)
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Samuel Jackson replied to John McEvoy
Hi John, the regions of galaxies we consider to be habitable are discussed in the previous section. Combining the locations dicussed previously with the text above about dark matter we arrive at a rough estimate for regions in a galaxy where stars may form life-bearing planets.
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Samuel Jackson replied to Doug Karo
I interpret it to be due to the graviational interactions from dark matter potentially causing problems for star systems.
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Samuel Jackson replied to Maxi Weigert
It is a case of having more stars means there will be more supernovae within this region than in outer regions where there are less stars. There isn't an increase in number density of supernovae, just an overall increase in number. :)
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Samuel Jackson replied to Freek B
I believe it is the faint grouping of stars roughly North East of the very bright object on the left of the frame.
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Samuel Jackson replied to Freek B
Yes, by 'sufficiently old' the article is saying that it must be of sufficient age to contain elements from previous generations, rather than saying it 'must be old' which the text may come across like.
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Samuel Jackson replied to Åke P
I'm so glad to see that the course has encouraged people to visit local observatories! It is a great experience. :)
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Samuel Jackson replied to Martin Hodnett
To return to this, I do not believe this to be the case.
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Samuel Jackson replied to Pete B
@DougKaro I imagine that the formulation of general relativity requires some mass parameter in the equation, and hence energy does not have that property when in that state.
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Samuel Jackson replied to Bill Ross
It is essentially impossible for them to have no motion (vibrational, rotational or translational) due to the requirement that they can't have zero energy. :)
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Samuel Jackson replied to Maureen Bowler
I don't think I'll be able to look when it launches! My nerves will be through the roof!
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Samuel Jackson replied to Bill Ross
As everything must have some energy above zero, they will have motion in some direction. When assessing the motion of all particles in a cloud, there will be some overall direction of movement of material in the cloud. This is the initial motion of constituent particles.
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Samuel Jackson replied to Mic Laird
It is possible, but without prior examples to aide our search and inform our models it makes sense to restrict our search in this way.
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Samuel Jackson replied to ALICE LORETTA MASTACAN
They are in what we call 'local habitable zones'. The moons of Jupiter can be hotter due to tidal forces from Jupiter heating the cores of these moons.
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Samuel Jackson replied to Ian Clark
The solidification of Mars is largely due to it's size. As it is quite smaller than Earth it's core solidified much faster, and hence the dynamo effect generating the magnetic field could not continue.
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Samuel Jackson replied to James Simes
Yes it is. Hopefully one day, somehow, we will be able to look back on our galaxy and take a photo of it!
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Samuel Jackson made a comment
Congratulations to everyone for making it through a tough week! The topics covered this week are very difficult to wrap your head around even for us who do this for a living, so I am thoroughly impressed with the discussions and questions I have seen this week!
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Samuel Jackson replied to Dave Lloyd
Unfortunately it is very hard to launch such large telescopes due to the limit payload capacity available of current rockets.
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Samuel Jackson replied to Maureen Bowler
The James Webb Telescope will be an amazing resource. I do hope that the launch goes well, and the extremely complex unfolding procedure goes off without a hitch!
Video of the procedure:
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Samuel Jackson replied to Alyson Kelman
I echo the comments of @HelenB and @MartinHodnett
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They become elliptical as the collisions are chaotic and random, and throw the entire system into disorder instead of the ordered rotation seen in spiral galaxies.
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Samuel Jackson replied to Helen B
Unsure specifically about Earth, but the space between stars is so large that even in these 'collisions' of galaxies, no matter will actually likely collide. So all problems for Earth will be due to gravitational effects (e.g. the Sun getting flung out of the Galaxy very quickly).
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Samuel Jackson replied to Helen B
It won't be entirely empty, but just so little matter it will be essentially empty.
Even the space between stars (interstellar space) has very little matter, just that intergalactic space has even less matter.
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Samuel Jackson replied to Bill Ross
@BillRoss All groups of material will have some level of what we call 'angular momentum' due to the motion of the constituents.
Objects within one galaxy will mostly all rotate around the centre in the same direction as objects that don't will likely collide and be removed from a system over time.
All galaxies aren't required to rotate in the same way...
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Samuel Jackson replied to Alan Thomas
It is certainly an interesting object, and while I hope it does go supernova soon I'm not getting my hopes up of seeing it within my lifetime!
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Samuel Jackson replied to Helen B
I certainly hope so! I hope there is an entire community out there somewhere in the universe. We shall have to wait to find out!
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Samuel Jackson replied to Helen Ashton
Our sun will certainly be long gone by the time that any of this becomes relevant. I do hope that some remnant of humanity will still be around somewhere in the universe, exploring and expanding our knowledge!
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Samuel Jackson replied to Helen B
Hi @JAIMEHERRERAFARIA, we have no been able to observe other universes if they do indeed exist. As it stands all of our observations have only revealed one universe, the one we live in. :)
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Samuel Jackson replied to JAIME HERRERA FARIA
Hi @JAIMEHERRERAFARIA , our current observations all point towards this theory being the correct one. If some other evidence were provided that contradicts this, the scientists would of course adjust theories accordingly to best fit the data available. :)
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Samuel Jackson replied to Pete B
@BarbaraN. As far as I am aware, no neutrons stars have been detected close enough to Earth to cause any harm. If one were pointed at us from very close range, then there could be some effect depending on the type of emission.
When Betelgeuse goes supernova, it will not cause any bad effects on Earth as the outward solar pressure at the Earth is still...
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@DougKaro Without understanding dark energy I don't think we can really say. It may be the case that the expansion between gravitationally bound objects is too small to detect with current techniques and instruments. The universe would continue to expand between objects that are not gravitationally bound, however.
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Samuel Jackson replied to Karen Wells
@ClaudiaMcPherson Indeed we did, a great loss to us all.
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Samuel Jackson replied to Pete B
@DougKaro Unfortunately relativity is quite beyond my speciality in observational astronomy so I wouldn't like to speculate much further on matters somewhat unfamiliar. I see your logic and it does make me question my interpretation too, however.
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Samuel Jackson replied to Pete B
@ALICELORETTAMASTACAN Yes that follows my general understanding of it.
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Samuel Jackson replied to Tom Dussman
@TomDussman To be honest I can't provide an answer to that as we simply don't know. However the current theory of dark energy suggests that it is some intrinsic energy within the universe that is driving the expansion of the universe. Hence I would suggest the 'pushing out' approach as opposed the the 'pulled out' approach, especially since we have no real...
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Samuel Jackson replied to Margaret Franklin
I think it is exciting that there are still so many questions to be answered! In my opinion it would be very disconcerting to be left with no questions except for 'what do we do now?'.
