Picture I took Friday Night and gif’ed up of Ursa Major/The Plough (full info on Flickr here). What’s the difference?
Both The Plough and Ursa Major are asterisms. This is the name given to a group of stars joined together to create a pattern. Like many asterisms, there’s more than one way to draw the lines to form Ursa Major (Latin for “Larger Bear”), so don’t be surprised if you’ve seen something different out there.
A constellation nowadays is one of 88 areas of sky with well-defined borders recognised by the International Astronomical Union (IAU), each named for an asterism they contain. Astronomical objects can be located by the constellation they’re in. Bode’s Galaxy (M81) and the Cigar Galaxy (M82) are both in the constellation Ursa Major, even though they’re not within the asterism itself (they’re located above the bear’s head).
All human history happens in the last 15 seconds of the cosmic calendar.
Neil DeGrasse Tyson (via mrserialx)
Really? Back of an envelope calculation:
Calendar = 12months => Universe time = 13.8 billion yrs
1month => about 1 1/8 billion years
1 day => 3/80 billion years = about 35 million years
1 hour => about 1.5 million years
1 minute => 25,000 years
15 seconds => about 6500 years.
… and ancient Mesopotamian cuneiform script dates back to around 3500 BC… so pretty damn good. I guess where you start the human history clock is much of a muchness, but this analogy seems good to a couple of seconds. How about that :)
Each second comes out to about 433 years, give or take maybe a decade in rounding errors.
Dr. Neil deGrasse Tyson has an important message about proper attribution.
I THOUGHT THIS WAS AN ADDED CAPTION BUT THEN I WENT TO THE VIDEO AND IT’S REAL
NEIL ACTUALLY SAID THIS
WHAT A TIME TO BE ALIVE
If you want to help your favourite Science research please, please do. It’s not just about getting the right source so people can follow the trail, although that’s important too; if you source correctly, the research will get more funding and you’ll see more of it.
In the UK, we’re currently doing the Research Excellence Framework, or REF. Departments in institutions have to write a hefty report on all the research they’ve done over the past five years. Part of that is an impact statement which includes impact on the public. Not much market-ready technology comes out of blue-skies research like astronomy. But astronomy is great at one thing - inspiration.
If you source the images and research you use correctly by citing the authors and year (e.g. Smith et al. 2013) and even including a link to the paper, scientists can find where they’ve been cited in places like tumblr and record comments. We need to show that our research and our effort in publicising it has encouraged people to take up science/physics/astronomy in some way, whether that’s as a hobby, in school or a career path. The holy grail of comments would be, for example “Wow, that looks and sounds so exciting, I want to be an astronomer now!”
If users don’t cite in the first post, we can’t find these comments for the REF, our impact is under-estimated, we’re ranked poorly and we lose funding. Simple as. So please, please help us!
Beautiful photos of the assembly of the James Webb Telescope.
The James Webb Space Telescope (JWST) is a large, infrared-optimized space telescope. JWST will find the first galaxies that formed in the early Universe, connecting the Big Bang to our own Milky Way Galaxy. JWST will peer through dusty clouds to see stars forming planetary systems, connecting the Milky Way to our own Solar System. JWST’s instruments will be designed to work primarily in the infrared range of the electromagnetic spectrum, with some capability in the visible range.
JWST will have a large mirror, 6.5 meters (21.3 feet) in diameter and a sunshield the size of a tennis court. Both the mirror and sunshade won’t fit onto the rocket fully open, so both will fold up and open once JWST is in outer space. JWST will reside in an orbit about 1.5 million km (1 million miles) from the Earth. (x)
Source: Flickr / gsfc
Please read it all, including the comments if you can! Choice quote, I really agree with it, and it can sneak up on you:
“Doing a PhD will break you. It’s pretty much designed to break you.”
I also agree with this blogpost fully. A success story that is as realistic as one will find in academia. Vital advice. Use it.
We are not simply stardust…
I’ve seen that Lawrence M. Krauss “… You are all stardust. You couldn’t be here if stars hadn’t exploded, because the elements - the carbon, nitrogen, oxygen, iron, all the things that matter for evolution - weren’t created at the beginning of time…" quote being bandied about and I need to say a couple of things about why that’s not entirely true. Sorry.
Now, those elements (the carbon, nitrogen, oxygen, etc) are necessarily the remnants of some star. The giveaway for the fact the star exploded is down to the fact we find radioactive material in the earth’s crust, where it simply decays. Going back in time, these radioactive elements must have formed somewhere, and the formation of the earth was probably not violent enough to spur nuclear reactions with enough energy to produce these elements. Radioactive materials must be formed by smashing heavier elements together, for which, in the vacuum of space, those conditions only really exist when a star goes supernova. Best guess is the rest of our elemental make up (the atomic weight of iron and smaller) came from the same supernova, but hey, where you find molecular clouds, made up of stuff like molecular hydrogen and carbon monoxide, the conditions tend to be right for star formation too. Such elements could have been created in some other kind of star, not just an exploding one.
I digress… your body, by the number of atoms, is dominated by hydrogen; around ~67% by elemental abundance. Hydrogen is not created in stars - in stars, it is fused to allow the release of energy by nuclear fusion, in turn creating heavier elements. Maybe we get some hydrogen back when the star goes supernova? … putting all that explosive supernova energy back into the atoms the star has built, back into separating them into hydrogen atoms. Maybe, but not much. Basically, there has only ever been one source of hydrogen which was the creation of the universe: the Big Bang. Without a universe, there is no such entity as space-time and thus, no dimension as time. The Big Bang was itself the beginning of time.
Most of your hydrogen atoms have been around since the dawn of the universe. And sure, yes, evolution couldn’t continue without your oxygen, carbon, nitrogen, iron, etc. But the most basic building block of all life, and thus very necessary for evolution, was created some 13.7 billion years ago in the same instant that the very fabric of space-time came into being.
The Administration shares your desire for job creation and a strong national defense, but a Death Star isn’t on the horizon. Here are a few reasons:
However, look carefully (here’s how) and you’ll notice something already floating in the sky — that’s no Moon, it’s a Space Station! Yes, we already have a giant, football field-sized International Space Station in orbit around the Earth that’s helping us learn how humans can live and thrive in space for long durations. The Space Station has six astronauts — American, Russian, and Canadian — living in it right now, conducting research, learning how to live and work in space over long periods of time, routinely welcoming visiting spacecraft and repairing onboard garbage mashers, etc. We’ve also got two robot science labs — one wielding a laser — roving around Mars, looking at whether life ever existed on the Red Planet.
- The construction of the Death Star has been estimated to cost more than $850,000,000,000,000,000. We’re working hard to reduce the deficit, not expand it.
- The Administration does not support blowing up planets.
- Why would we spend countless taxpayer dollars on a Death Star with a fundamental flaw that can be exploited by a one-man starship?
If you are counting how many hours a week you are working, you probably don’t like your job very much.
The thing you spend your life on shouldn’t feel like a transaction to you. I have no idea how many hours a week I worked in grad school, because I wasn’t thinking about it at the time. I could probably go back and estimate, but why? It varied week to week, just like the hours I work now. Some weeks are efficient and productive and require less time, and some are slow, arduous, and irritating. Just like now.
I know we’d all like to think that the only thing standing between us and awesomeness is a single number– a magical tipping point beyond which success is certain (I’m looking at you, Malcolm Gladwell). Unfortunately, that’s not true. You can spend a lot of time trying to do something better and only see incremental gains, even when other things come naturally and require little investment of time. That’s not to dismiss hard work, which I think often takes a back seat to the idea of “talent” in our common lore– talent is usually just hard work that went well. But ultimately, success is not a product that can be yours for a set purchase price.
The way you feel about your work is like the weather on a long hike– changing, fickle, with days you will always remember and days you will try to forget. The calculus of whether it’s worth it to go hiking at all is up to the individual.
Aimed at grad students/one-day grad students - this email encompasses a mentality in the field that you may have to deal with. Be warned.Does everyone remember the famous letter from Caltech chemist Erick Carreira to his unruly, unmotivated, and apparently unprincipled laboratory assistant? Or subsequent discussion about the compulsory workaholic culture of academic chemistry which followed the letter’s publication in 2010?
“The Chinese Proof” of the Pythagorean theorem (the little orange square is
a², the medium orange square is
b², and the large orange square is
The righthand picture above appears in the Chou pei suan ching 周髀算經 (ca. 1100 B.C.), for the special (3,4,5) pythagorean triple….
…the earliest known proof of Pythagoras is given by Zhoubi suanjing (The Arithmetical Classic of the Gnomon and the Circular Paths of Heaven) (c. 100 B.C.E.-c. 100 C.E.)
[T]his proof, with the exclamation `Behold!’, is due to the Indian mathematician Bhaskara II (approx. 1114-1185) …
Jöran Friberg … presented convincing evidence that the … Babylonians were aware of the Pythagoras theorem around 1800 B.C.E.
The Euclidean proof is similar: literally forming squares using the lengths of the sides of a right-angled triangle.
“S*** Astronomers Say” by the “.astronomy 4 Hack Day” group.
I know these kinds of videos are rather overdone, but for those interested in an career in Astronomy, you’d be wise to pay attention to what you’ll be hearing day in, day out!
- IDL is a coding language used by astronomers (and climate scientists). More astronomers are moving onto another language called Python nowadays. FORTRAN 77 is an old version of the coding language FORTRAN; many people still know these old versions because they had to run and edit codes their supervisors edited that their supervisors edited written by their supervisors… and so on and so forth.
- Many (but by no means all!) astronomers use UNIX based operating systems like LINUX and Mac OS’s instead of Windows because they find them easier to code with, leading to distaste for Microsoft products. Apart from Powerpoint it seems.
- A common thing to hear is that ‘50% of all results in Nature [a top scientific journal] are sensationalist/wrong’. Is it true? I’m not sure yet, but usually whoever says it is trying to be witty so maybe they’re exaggerating to make themselves feel better about not getting their paper in the journal ;).
- MCMC, or the Markov Chain Monte Carlo method, is a way to solve a system of equations to find the best solution. It’s a bit complicated but what this video is getting at is that it’s treated like a magic solution at times and is really popular to use at the moment.
- “What time is it in Chile?” Many astronomers have collaborators all around the world, so they will have teleconferences and email each other all the time. If you want and answer from someone today, you better find out what time it is in whatever country they are first!
- “Has anyone got a dongle?” A LOT of astronomers have macbooks (and other Apple products) and have to give presentations. With that comes the issue of needing a dongle to connect to a projector and no one ever brings their dongle to conferences!
- “Hawai’i/Australia/Chile/South Africa again?” These are where all the big telescopes are, and astronomers get a lot of travelling done covering observing shifts. So much so the travelling can seem like a chore at times for some people!
- “Rumormill” is where people post up information regarding jobs in astronomy and who got what offer. Postdocs and graduating PhDs especially are attached to the site.
- Astronomers are astronomers, not business people, and are on the whole only okay at writing and performing presentations! Someone invariably falls asleep, and common and soul/research-destroying questions get asked at the end.
- “Segmentation faults” are computational errors that are notoriously difficult to debug.
- Bayesian/frequentist are two different ways of understanding statistics (you probably learnt frequentist stats in school).
- Astro-ph is a site where all new papers in astronomy (and physics) are posted as a free alternative to journals. Usually people wait until their paper is accepted into a journal before posting to astro-ph.
I hope that helps people!
I love this :)
And following up from astronomnomy:
- I wrote a bit about MCMC or Markov Chain Monte Carlo a while back for the keen.
- "What time is it in Chile?" : Chile has a whole bunch of observing facilities and is the home of many new telescopes, such as the Very Large Telescope (VLT), Visible and Infrared Survey Telescope for Astronomy (VISTA), Atacama Large Millimeter/submillimeter Array (ALMA), etc …[on a separate note: astronomers are fond of acronyms]. The subtext behind the lead up to the question is usually ‘I emailed X a question and they haven’t answered in the last couple of hours. If they’re not in the office, they’re probably observing, and if they’re observing, it’s probably at one of those fancy-pants telescopes in Chile…at night… so…’
- On those after-talk questions.. the question on magnetic fields is a doozy. Unless you’re specifically studying magnetic fields in astronomy, chances are you won’t have considered them… they’re considered a known unknown.
- I’m going to be fair about the statement on Nature… it is something you hear off astronomers, but it’s quite flippant so let me quickly reason it out. Nature deals with high impact, cutting edge, scientific research and results of that research. And with cutting edge research, you’re more likely to find things that have never been seen before, which might ruffle a few preconceptual feathers, but that sometimes turns out to just ruffle something else.
- Finally, it really is usually Prof. Hans Walter-Rix who brutally cuts down your research after being asleep at the front through the whole of your talk.
XKCD has started explaining “what-if” scenarios with hard physics. In the first edition, XKCD answers the question “What would happen if you tried to hit a baseball pitched at 90% the speed of light?”. The explanation is straight, which only adds to how hilarious it is:
These gamma rays and debris expand outward in a bubble centered on the pitcher’s mound. They start to tear apart the molecules in the air, ripping the electrons from the nuclei and turning the air in the stadium into an expanding bubble of incandescent plasma. The wall of this bubble approaches the batter at about the speed of light—only slightly ahead of the ball itself.
Tomorrow Venus moves in front of sun (or ‘transits’), and Brisbane is perfectly placed to observe both the ingress and egress of the transit. If you miss it, the next transit is in 2117, so the chances are you won’t be alive to see it. However, if you don’t live in Australia, we have a telescope linked to a camera, and will be streaming the transit over the web. Ingress starts at 08:16 AEST tomorrow morning, so those of you in the UK still awake at 11:16 tonight will also be able to see it.
Unless it’s cloudy of course…
Last chance you’ll get this lifetime!
Happening now! NASA link from Mauna Kea with commentary if you fancy :)
Hi! Just reposting an infodump I made for r/cosmology on reddit in case someone else is interested.
“Although this simulation isn’t new, it’s over a year old. I’ll just info dump about simulations if you don’t mind.
So the simulation itself is worth mentioning. The code used is called AREPO, and it’s ridiculously clever. Broadly, simulation codes work in one of two ways; on a grid, or with particles. Grid simulations split their simulation box up into tiny cubes (cells) that each have associated with them numbers for a temperature, energy, density, amount of hydrogen… etc. At each time-step in the simulation, physics equations (and approximations to them in some cases) are applied to the cubes and their neighbours and the numbers are updated to show e.g. gas moving from one cell into another.
Particle simulations do something different a bit different. Particles are spread out in the box, and particles are assigned a mass. The particles then move in the box under the influence of gravity, so the particles gravitate towards the densest point, giving automatic higher resolution in the denser areas. The resulting particle pattern is smoothed out to calculate the density and other values.
AREPO combines these two methods using a moving Voronoi mesh (here ’s what it looks like, I can’t find a video/gif but it’s mesmerising to watch). In comparison tests it seems to reproduce and keep turbulence better than a particle code called GADGET, which is interesting. AREPO uses the same particle solver as GADGET to do the dark matter portion of the simulation, mesh is hydro only. AREPO and GADGET were both written by Volker Springel for the most part.
This particular simulation isn’t a big one by any means, which is to be expected as I think this is just the proof of concept simulation? Looking at the vid description it’s a 20 Mpc box which means that at the output time of z=2 (3.3 billion years after the big bang) when this snapshot was taken, the box is ~7 Mpc wide or in more easily pictureable terms, 23 million light years, or 700ish Milky Way galaxies end to end.
The simulation itself shows the distribution of gas in the box and highlights some large galaxies and galaxy mergers. They’re drawing attention to the structure of the galaxies and the tidal streams of gas during the mergers to show how well resolved and complicated they are.
Tl’dr, this simulation is a showcase for the AREPO code.”
The [academic] job market is brutal, we all know that. Grad school is a gamble, and most people shouldn’t take it — a good thing to point out. But this business of “The Big Lie” … deliberately brainwashing students about the “life of the mind” in order to suck them into exploitative … careers…. simply isn’t true.
The lack of data, the bad career advice, the unrealistic expectations, all of these are not the product of some conspiracy, but of a poorly organized and often anarchic system that has developed without any overall plan at all. To improve it, we need to think about the systemic patterns that produce it, not seek out some tenured villains to blame it on.
Take the lack of placement statistics. [It’s not] that “Most departments will never willingly provide that information because it is radically against their interest to do so.” … They won’t provide that data because in most cases they don’t have it. Large graduate programs in the liberal arts are strikingly anarchic places…. It can be difficult to get a list of the graduate students who are enrolled, let alone those who aren’t around any more.