For me it is the fact that our blood contains iron. I earlier used to believe the word stood for some ‘organic element’ since I couldn’t accept we had metal flowing through our supposed carbon-based bodies, till I realized that is where the taste and smell of blood comes from.
A day on Venus is longer than a year on Venus. One day takes 243 Earth days, while a year takes 225.
Maybe it’s not “well known”, but still interesting in my opinion.
I mentioned this one to my friends the other day and it took so much convincing before they actually believed me! Definitely an interesting one. Venus also spins the opposite direction to all the other planets in the solar system, meaning the sun rises in the west and sets in the east.
I get people telling me “no, that’s impossible” every time I mention this fact.
Wouldn’t spinning in the opposite direction indicate that it’s axial tilt is flipped or something?
The leading theory is a moon sized object hit it with enough force to spin it backwards.
Ok hold up so the way I’m understanding this is that its tilt (day) is slower than it’s rotation around the sun (year). Is that right or am I way off?
You’re close. Not the tilt of its axis, but its rotation around its axis (day) is slower than its rotation around the sun (year).
Earth’s axis is tilted at about 23 degrees, which causes the seasons. Venus, by contrast, is tilted only about 2.6 degrees, and thus basically doesn’t have seasons in a comparable way.
Earth’s axis does very slowly wobble around (precession). Over long enough time scales, this affects the seasons, and it means the North Star has not always been aligned with Earth’s North - once, North pointed at a patch of black sky and the North Star was just another star appearing to rotate around that arbitrary point.
I’d imagine Venus’s axis might also wobble at least somewhat, but I haven’t actually looked into this at all.
Thinking about this sent me down a rabbit hole because the day and year lengths are so extremely close to each other, and Venus rotates around its axis clockwise (unlike the other planets) while spinning around the sun clockwise, and its tilt is so slight… so as it spins around the sun, it rotates just enough to keep one side facing the sun almost all the time. I ended up googling whether it was tidally locked, like the moon is to Earth (such that we only ever see one side and it never changes) - and apparently it would be, but its atmosphere is so wild that it prevents tidal locking. But it almost is. It kinda has a dark side, and a light side, like the moon, but there’s just enough mismatch between the yearly rotation the axial rotation that the side facing the sun changes slowly. This is the first article I found.
From that article, it seems like the daylight hours you’d experience standing on the surface of Venus would be 117 Earth days of light, before it got dark again. So the sun would rise, and then you’d have about half a Venus year (aka about half a Venus day, too) of daylight before you’d see night again. And then it’d be night for the rest of the year. But still scorching hot because atmosphere.
Anyway this is blowing my mind a bit. I feel like I should have known this - I used to be obsessed with astronomy when I was little. Maybe I knew it once and forgot. I don’t know. But dayum. Planets are cool.
I’ve seen this fact somewhere before, but I still am unable to grasp it in my mind
Short: It completes a full 360° of the sun before the planet itself does a full 360° spin.
A few sentences longer:
In planet Earth human terms, we have defined one day as “how long it takes the planet to do a full 360 degree rotation”. Example: You spin a basketball on your finger and it does one full rotation.
A year to us is “how long it takes the planet to go around the sun”. Example: You hold a basketball out in front of you and you do one full rotation.
It doesn’t. Gravity is caused by mass not spin. The planet’s rotation about it’s own axis will create a centrifugal effect that offsets gravity, but the effect is negligible for anything rotating as slow as planets.
The others already said the core aspect, but to get specific: the difference between your weight on the pole and your weight on the equator differs only by like .5% or something like that. This is the difference between spinning and not spinning (centrifugal force and no centrifugal force). (And also the difference in radius, since the Earth’s rotation makes it a tiny bit flatter than a perfect sphere would be)
Planets and stars and galaxies are there. You can see them because they’re right over there. Like, the moon is a big fucking rock flying around the earth. Jupiter is even bigger. I see it through a telescope and think “wow that’s pretty,” but every once in a while I let it hit me that I’m looking at an unimaginably large ball of gas, and it’s, like, over there. Same as the building across the street, just a bit farther.
The stars, too. Bit farther than Jupiter, even, but they’re right there. I can point at one and say “look at that pretty star” and right now, a long distance away, it’s just a giant ball of plasma and our sun is just another point of light in its sky. And then I think about if there’s life around those stars, and if our star captivates Albireoans the same way their star captivates me.
And then I think about those distant galaxies, the ones we send multi-billion dollar telescopes up to space to take pictures of. It’s over there too, just a bit farther than any of the balls of plasma visible to our eyes. Do the people living in those galaxies point their telescopes at us and marvel at how distant we are? Do they point their telescopes in the opposite direction and see galaxies another universe away from us? Are there infinite distant galaxies?
Anyway I should get back to work so I can make rent this month
If I point my finger at one of those galaxies, there’s more gas and shit between us within a hundred miles of me than there is in the rest of the space between us combined
What’s even more fascinating is that most of the stars we see in the sky are afterimages of primitive stars that died out long ago yet they shine as bright as the stars alive today
That doesn’t seem right. The galaxy is only 100,000 light years across (give or take) and the life span of stars is measured in billions of years.
Most of the stars we see are in our galaxy, so at most, we are seeing them as they were 100,000 years ago, which means that the vast majority of them will still be around, and looking much the same as they did 100,000 years ago.
Not too sure where you got that number from. From what I can find, the radius of the observable universe is estimated to be about 46.5 billion light-years.
Edit: I see now that you are talking Galaxy. That’s different.
I can really relate to this. I remember a weird night in my teens where I must’ve spent at least an hour staring out of my bedroom window at the moon, because really for the first time I’d had the exact same thought. It’s right there. It’s so easy to get desensitised to that and to just think of it all as an image projected on the sky. The thought has never really left me and even now I still linger on the moon every time I see it and try to acknowledge that it is a 3 dimensional object lol.
In the same vein, I like to remind myself that every field in physics is literally happening all around me, right now, and it always has been, in fact, I’ve never seen anything without these invisible fields in it and for some reason, that really makes me super aware of our place in the order of magnitudes.
It’s wild we can see so much further down than up.
First time I saw Jupiter through a telescope I got hit hard by the feeling: “Oh shit, that giant monster is real”.
A moon isn’t that strange, our moon is.
First, it is massive compared to Earth. The mass of the Moon is so large that it messed with definitions of planets and plutinos.
Second, the Moon’s size and distance from Earth is a near match for the Sun’s, which is really rare.
And for a strange fact, the Moon is about as reflective as worn asphalt. The Moon looks white in photos of just itself, but it is a dark grey when in photos with Earth.
There’s a giant ball of extremely hot plasma in the sky and we aren’t supposed to look at it. What is it hiding? Surely if someone managed to look at it long enough, they would see the truth!
Time relativity always boggles my brain, I accept the fact but I find crazy that if I strap my twin and his atomic clock to a rocket and send them out to the stratosphere at the speed of light, when they return he’ll be younger than me and his clock will be running behind mine. Crazy
Also the idea that light is both a particle and a wave always messed with my head because I wanted to know why does it decide to change and when? And the answer is that light is always a particle and always a wave at the exact same time.
It is a wave particle.
And it is possible from light alone to build both an electron and a positron as demonstrated in a 1999 laser science experiment in New York.
I usually interpret this as behaviour: photons are not “particles” or “waves”, photons are photons. They just behave as waves and as particles, depending on how you’re looking at them.
Note that even things with a resting mass (like you or me) are like this, too. It’s just that, as the mass increases, the wave behaviour becomes negligible.
The crazy thing is there are actually two double slit experiments, and that light can tell whether or not you are actively observing it or not, and decides whether or not to actually exist as a wave or particle.
It’s even crazier because you don’t need to reach the speed of light. It’ll happen in a smaller degree for any speed. Even in mundane conditions.
For example, if your twin spent four days in a 300km/h bullet train, for you it would be four days plus a second.
Usually this difference is negligible, but for satellites (that run at rather high speeds, for a lot of time, and require precision), if you don’t take time dilation into account they misbehave.
(For anyone wanting to mess with the maths, the formula is Δt’ = Δt / √[1 - v²/c²]. Δt = variation of time for the observer (you), Δt’ = variation of time for the moving entity (your twin), v = the moving entity’s speed, c = speed of light. Just make sure that “v” and “c” use the same units.)
Yes I knew about that and I’m glad that doesn’t make it crazier for me, instead it makes it easier to accept. If it were something that happened only after hitting some arbitrary speed value I’d be a lot more mentally damaged
I wonder how long it would have taken for us to figure out time dilation in Einstein hadn’t predicted it. I wonder if it would have taken until we observed it with satellites.
Without Einstein, I think that the discovery of time dilation would be delayed by only a few years. There were a lot of people working in theoretical physics already back then; someone else would inevitably dig through Lorentz’ and Poincaré’s papers, connect the dots, and say “waitaminute time might be relative”. From that, time dilation is a consequence.
In special I wouldn’t doubt that Max Planck would discover it.
I’m saying that because, in both science and engineering, often you see almost concurrent discoveries or developments of the same thing, because the “spirit of a time” makes people look at that aspect of reality or that challenge and work with it. The discovery of helium and the development of aeroplanes are examples of that.
The part that I understand in the intellectual sense, because I know or at least used to know how it follows from the math, but which just doesn’t feel like it should be the case, is the whole “relativity of simultaneity” aspect of it. That there isn’t an objectively true order in which events happen in, if the events in question aren’t linked by cause and effect. That is to say, it is possible for one person to see an event A happen before another event B, a second person to see the two happen at exactly the same time, and a third to see event B happen first and then event A, and for all three of them to be equally right. It just feels like, on some level, there ought to be one objectively true order to time, a single valid timeline that all events can be placed in relative to eachother, and for time not to work that way feels so absurd as to not even be able to articulate why the idea feels wrong.
Here’s something I just ran into looking stuff up for my comment: GN-z11 is one of the farthest galaxies we’ve ever seen. Thanks to the expansion of the universe, at a distance of over 30 billion light-years, it has to be moving away from us at over twice the speed of light.
What the fuck does that mean, temporally? Like, forget the speed of light, time dilation has to do with space and relative speeds. If I’m moving at near the speed of light relative to you, then my clock will physically tick more slowly. What happens if I’m moving over twice the speed of light? Is the real life GN-z11 in our reference frame moving backwards in time at over twice the rate we’re moving forward?
I can’t find any reference that says it’s moving away from us at twice the speed of light, which would violate Relativity. The fact that it is further away from us in light years than the age of the universe in years, is due to the fact that the space itself is expanding.
The thing is, it’s moving that fast because of the expansion of space. ≈30 billion light-years over ≈14 billion years equates to over twice the speed of light. Does that mean there’s no crazy relativistic time dilation, and time is moving normally for them in our frame of reference, since they aren’t physically moving, it’s space that’s expanding? That’s just as wild to my brain
From what I understand, you are always travelling at the speed of light through space/time, but when you move at high speeds through space that shifts the proportion of your speed out of the time dimension. And a photon travels only through space, experiencing no time between the time it was emitted and the time it was absorbed. What I just can’t wrap my head around is the concept of travelling at some speed without involving the time dimension at all.
Probably one of the most memorable and pivotal moments in my life was when my college professor showed us the origins of relativity and how Einstein came to the conclusion that E = mc^2
It’s a proof that only took about 10 minutes to explain, and the mathematics really aren’t that difficult to understand by most people. The geniuses in the fact that Einstein started by explaining how calculating relative motion meant that time had to be a variable that could be different depending on who the observer was. This in itself is an incredible observation, but you can take this to the extent to literally prove that mass and energy are directly related to each other. It’s absolutely wild and one of the most sublime equations ever made.
I wish we could test this out with only simple apparatus. Unfortunately the common people do not have access to satellites or nonstop bullet trains.
Not exactly bizarre, but it’s fun to learn that the delicious fragrance of shrimps and crabs when cooked comes from chitin, and chitin is also why sautéed mushrooms smell/taste like shrimps.
And since fungi are mostly chitin, plants have evolved defenses against fungi by producing enzymes that destroy chitin, which is how some plants eventually evolved the ability to digest insects.
EDIT: a previous version of this post mistakenly confused chitin with keratin (which our fingernails are made of). Thanks to sndrtj for the correction!
Chitin is not produced by mammals.
Fingernails are composed primarily out of keratin (same as hair and skin).
Wow I didn’t know this and I’ve never felt a similarity between seafood and mushrooms either in flavour or smell. But, still a cool fact.
It’s one of those things that feels really obvious if you cook a lot of east/south Asian dishes - shrimp sauce and mushroom soy sauce have a pretty similar aftersmell to them because they’re so concentrated
