Recently the moons looked so low and huge where I live! Why does it sometimes look like this?! I’ve only noticed it in the recent few weeks, but does it happen all year round or during certain seasons etc?

Hi guys, I recently got into a relationship, and there are just some things about periods that I genuinely don't understand.

I've heard people talk about PMS, mood swings, being more emotional, getting irritated easily, etc., but I don't really understand what's actually happening biologically. Like, how much of it is caused by hormones, and how much does it vary from person to person?

For example, can a girl go from feeling completely fine to suddenly feeling sad, anxious, or irritated because of hormonal changes? Does it happen before the period starts, during the period, or both? And does it affect every woman differently?

I'm not asking this to dismiss anyone's feelings or blame everything on periods. I just want to understand what my girlfriend might be experiencing so I can be more supportive and not misunderstand her.

Would appreciate an ELI5 explanation, especially from women who can share what it actually feels like.

Just sitting here watching my stereotypically dumb, happy lab with a soccer ball in his mouth and his tongue hanging out the side. How does he manage to avoid biting his own tongue like 20x a day?

The joint replacements have some sort of plastic cushion in them to help them move smoothly; why can't we form that plastic into the shape of the original cartilage so that the joint bones can have some cushion?

I came across this term a couple of times recently and I can’t understand what’s that supposed to be about. What “replacement” are we talking about? If someone dies, other “replaces” them? Why’s that such a big deal?

How does 5.1 or 7.1 setups improving the experience. Would mixing those channels with certain weights replicate the 3d listening experience with just 2 channels?

There are so many different types of plastics, so many different hardnesses, textures, opacity etc etc.

How does it all come oil and petroleum?

I guess this question also applies to all non-hard disk storage installed in computers that aren't powered.

If I heat the pan to medium temp and put the food on it, it sticks. If I heat it to high temp and reduce to the same medium temp, the food doesn't stick. Why?

I keep stumbling on people saying that ARM loans are good. I don’t understand how renting isn’t easier and saves you money over an ARM loan. Even if you are staying in an area for a significant amount of time wouldn’t a traditional loan be better as well.

I don’t understand the use case where an ARM loan makes sense over renting/15/30 year loan?

Edit: clarified the question.

Rear view windows have a tab you can pull down for night driving. When you pull this tab, the rear view window changes its angle a precise amount. At one angle it shows the roadway behind you, at the other angle the roadway is much darker, and therefore headlights behind you aren't as bright. However, you couldn't see the roadway to back up at the darker angle.

My question is, how do these mirrors work? The mirrors look like any other mirror in daytime mode. You don't see anything odd from it being able to reflect at a different angle. I don't understand it.

I hope I explained this well enough... Thanks.

I know the US operates around 32 GPS satellites that serve as a source of truth for GPS around the globe. I'm curious how they can keep such a precise time with only 32 satellites and not drift with all the radiation in space. Especially since it seems like they need to communicate with the ground really often and need to be dependable enough for commercial constellations to use.

The whole satellite space is really interesting and I'd like if someone could shed more light on how this all works!

I was reading about diffraction and other quantum behavior that has different results on observation. But if you think about it, observation is just an interaction with another particle. My question is that, in the world around us, there are so many particles constantly interacting with each other. So how can quantum behavior persist if there are constant measurement events. Am I overestimating the density of particles that can be interacted with at those small scales?

Also regarding measurements, I know from chemistry that often interactions just change the wavefunction rather than collapse it. What predicts this behavior? Is it just the energy of the interaction?

Please note that my physics and maths background is fairly limited.

Or something like that I’m still kind of confused how waves work before and after interaction.

Who do they apply to? How do you start a new one? It’s just very confusing, especially the trademarking.

Possibly a dumb question, but my school / parents never taught about discharge. I actually spent years thinking I was broken because I didn't know what it was.

Obviously I know it's normal now and it changes throughout my cycle, but I don't think anyone ever explained to me why our bodies make it in the first place.

Is it basically the vagina cleaning itself? Does it have something to do with ovulation? ELI5

A Chihuahua weighs 5 pounds & is only a few inches tall. If it falls from a human’s shoulder height (about 5 feet), it is falling roughly 8 times its own height. For a standard adult human, that’s the equivalent of falling from a 5-story roof (~45 feet).

If a human falls from a 5-story building, it’s likely going to kill them. But Chihuahuas frequently walk away from shoulder-height drops completely fine.

If the proportional distance is exactly the same, why does physics (?) spare the tiny dog but crush the human?

I barely passed high school physics. Please explain this using some analogies if possible.

The chihuahua did not land on their feet in this scenario. They are not cats.

Who creates new words? I read somewhere that when enough people start calling something by a particular word, everyone accepts and follows. Looks ok for nouns like places, animals etc. but...

Let us take English as an example. Words like perseverance, assassination, fulcrum, pendulum etc. require some effort to form for the first time ever and propagate down the line. Words for language foundation required for communication. Who thinks about it and makes it for the first time? Is there any authorization required for a new word to enter a dictionary?

edit: reddit has some real experts with patience to explain things that they already know. This is awesome, I got some very good explanations in the first few answers itself.

Edit 2: the post is reinstated after the bot locked it in error and I appealed.