pavelcherepan

Stop dodging questions. Please get a relevant citation that shows that dust density in protostellar cloud can be so high as to block the light completely rather than being something like 10-a lot particles/m3.

Citation needed or just stop making stuff up.

Man, I wish I haven't used the "double-facepalm" card so soon.

That's the lamest excuse ever. You can't provide links too? It did. You just didn't make an effort to understand what it means... just like all other times.

I think it's high time you started proving something and providing supporting argumentation. What is your purpose in this discussion (an all other discussions for that matter)? You don't learn anything, every time you ask same questions as if those haven't been discussed already, you demand and don't give any evidence or calculations and generally act with a total disrespect to the accepted knowledge and search engines. Why don't you stop wasting everyone's time?

23% reduction in rotation speed is nothing? What is the magnitude you're talking about? POST SOME LINKS!

Yay! Nay! https://en.wikipedia.org/wiki/Angular_momentum#Conservation_of_angular_momentum Since the moment Sun became a main-sequence star it's radius has increased by a factor of 1.11, hence it's rotation should decrease by a factor of ~1.23. That is excluding any tidal effects that will also add to slowing it down.

Tell me, what can you make out of this graph that is relevant to your question? https://en.wikipedia.org/wiki/Sun#Main_sequence

Moon is ~1/80 of the Earth's mass and is about 63 Earth radii away. Jupiter is ~1/1000 mass of the Sun and is ~1000 solar radii away. As a result the tidal interaction of Sun with Jupiter is thousands of times weaker than in Earth-Moon system.

What you believe is irrelevant. Can you prove it? Yeah, that would be because Sun is tidally interacting with planets, notably Jupiter, and loses angular momentum as a result.

PMS Sun was moody and irritable. You can check this paper. http://adsabs.harvard.edu/full/1993ApJ...418..414P

Hans, I'm not sure this will be the case. 1. With lower tilt (20 vs the current 23.4 degrees) the territory that experiences polar day/night will actually decrease. You can check this by drawing a tilted and non-tilted Earth and see how light from the Sun will affect both hemispheres. 2. UK climate has nothing to do with tilt, it's due to the effect of Gulf Stream. Obviously, the change in tilt can result in Gulf Stream stopping and in that case UK and most of the Europe will have similar climate to Western Russia. 3. Not sure how you got to this conclusion. 4. Definitely not.

Why?! Why would Sun impart any momentum on a photon? What is the mechanism of it? P.S. Stop patronizing me.

It's on the page 3 of the paper published: http://journals.aps.org/prl/pdf/10.1103/PhysRevLett.116.061102

OK, let's try. You have a particle and from your POV on the Sun it's hanging in the same spot in the sky all the time. From the POV of the particle you're also in the same spot all the time, but for an external observer both you and the particle will be moving. Back to your reference frame. You see particle in the zenith. Is it there now? No. It was there 8 minutes ago when light reflected off of it. So now you try and shoot your laser at the particle. Should you aim at it's apparent position in the sky? No. Like I said before, it was there 8 minutes ago. Then should we aim at where the particle actually is at this moment in time, i.e. 8 minutes ahead of it's apparent position? Again no. By the time your signal reaches it, it will be ahead and you'll miss. This all boils down to the fact that you'd have to aim ~16 minutes of travel ahead of it's current apparent position and then you'll have a chance of hitting it.

Well, then you don't understand orbital mechanics. After all discussions we've had it's not surprising. You've already had a 300-page discussion of physforums on that topic. If you want to talk about habitability of Mercury create another topic. Stop hijacking your own discussions.

Shielded? How much dust do you think was there? Take a guess in particles/m3. I don't understand what you're doing. Are you trying to perform your own research of the topic and come up with your own number? In that case you really-really need to read up on planetary and star formation more and be ready to provide calculations. Otherwise, why would you think that existing research on the topic is inadequate? Do you think that a whole lot of scientists got it all wrong? And if that's the case, what is your reasoning behind it?

Scientists working on a project have calculated a wide range of templates for different phenomena that can cause major gravitational waves and each of those has very specific characteristics in terms of final wave form. So when the signal was received the team was pretty confident pretty much straight away that it was black hole merger.

It's not too hard to calculate if you know the direction the particle is moving. The angular velocity of the body at the same orbit as the Earth will be: [latex]\omega=\frac{2*\pi}{365*24*60} = 1.19*10^{-5} radians/min[/latex] We observe the particle an then aim the laser to 16 minutes ahead of it's observed position, because it was there 8 minutes ago and it will take another 8 minutes for the laser beam to reach it. Then we should aim at 1.19*10-5*16 = 1.9*10-4 radians ahead of it's observed location. And if the aim is good enough, we should hit it. Anyway, how is this relevant to the topic of discussion? What does this have to do with the age of Sun?

I'm pretty sure that that's nothing to do with "sideways motion of the Sun", whatever that is. It only has to do with the actual orbital velocity of the particle. No matter if it's in solar-stationary orbit, the particle is still moving in its orbit. And also the Sun-stationary orbit would have a semi-major axis of (with modern day Sun): [latex]a=\sqrt[3]{\frac{T^2*\mu}{4*\pi^2}} = \sqrt[3]{\frac{(25*24*60*60)^2*1.327*10^{20}}{4*\pi^2}}=2.16*10^9 m[/latex], which is within Sun's corona and the particle would evaporate sort of instantly. As far as I understand it, a photon wouldn't have any "sideways component" simply for the reason that from the instance the photon is created it's travelling at c. Adding a sideways component to its velocity would result in final velocity that can be above c, which is obviously impossible.

Is there any economical or scientific reason for manned missions to other celestial bodies? While manned mission will most likely be able to collect scientific data faster than unmanned drones these will be very limited in terms of duration of their stay and so devices like Mars rovers might be able to outperform a manned mission both in terms of amount of scientific data collected and at a fraction of the cost. Another option is a long-term manned research base, which, while being extremely expensive will not be as limited in terms of duration of stay and be able to collect scientific data faster than unmanned devices. Which one of these three is better in terms of scientific output vs cost? Bonus question: is there any point in sending people to Mars? Apart from the fact that it would be awesome.

Higher tilt - greater difference between seasons, lower tilt would cause the opposite. With a 45-degree tilt it's likely that polar ice caps might become seasonal, rather than permanent, which would raise the global water level and cause flooding of low-lying areas. Overall the climate changes will be dramatic.

Specific impulse if measured in seconds is the time that an engine can produce a thrust of 1 N using 1 kg of fuel. There is a direct relationship between SI and exhaust velocity, i.e. the higher your exhaust velocity is, the higher your SI will be. Not quite. With 10 engines you'll have a higher TWR and higher acceleration, but at the same time you'll use your fuel faster and in fact the final velocity with a 10-engine setup will be lower than with just 1 engine because you'll have to use fuel to propel the mass of those other 9 engines. Stick to 1 engine. EDIT: You could actually put a ten-engine design to a good use if you use the thrust of all 10 engines when you're in the inner Solar System and as close as possible to the Sun and then jettison 9 engines and continue accelerating using the remaining 1. That way you could make a good use of the Oberth effect and use your fuel more efficiently.

One of the most energetic cosmic ray particles ever detected - Oh My God Particle - had approximately the same energy as a baseball travelling at 90 km/hr and was travelling at 99.99999999999999999999951% of c.

It may be surprising but there's still a lot of discussion going about the origin of oil deposits, but most scientists agree that it was most likely plankton and microscopic algae that are responsible for oil formation. So no, your assumption is most likely incorrect. Even if complex organisms could have a part in oil we have now, there would be an immeasurably small amount of those compared to simple microscopic organisms. Nice find! That's a pretty small ammonite though. Either a young specimen or the rock is from lower Jurassic age when most ammonites were much smaller than later species.