New answers tagged

4

First, Pluto isn't a planet, and hasn't been for about a decade. It's a dwarf planet, and is better grouped with other small, rocky objects beyond Neptune's orbit, such as Haumea. These objects, and other minor planets, have more in common with objects in the Kuiper Belt and Oort Cloud than the eight planets of the Solar System.1 Therefore, we see a ...


8

I'll give this one a shot. Correction is welcome. Upper atmosphere temperature. It's not just elements that give a planet color, but the temperature of elements. When we examine what a planet looks like, we're basically talking about reflected sunlight from the planet's surface or atmosphere. With Earth, its atmosphere is transparent enough that its ...


1

Yes, Jupiter and Saturn have their own radiation belts. Jupiter's is extremely powerful, which is why all of Juno's sensitive electronics had to be radiation hardened and shielded inside a vault. It's also why Juno is going to be on a polar orbit doing flybys of Jupiter, instead of orbiting around it closely. These magnetic bands are indeed separated into ...


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Hohmannfan's answer is correct, but as I understand your question, you do understand the general idea correctly and the answer to your question is yes, no matter how eccentric the orbit, the planet spans equal areas over equal time, at least nearly perfectly. (more on that later) You're mistake is in calling the sectors "triangles". They're sectors of an ...


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That is not correct. The area is the total area between the two radius lines, so there is a curved side. Imagine you have two points almost 180 degrees from each other. Using just a triangle, the area is close to zero. Now, two points placed closely together can have the same area in between them. Then you have an equal are, but not equal time, so your ...


2

Well, I can't do the math, but if an intuitive answer is OK: If a planet is tidally-locked, can it have an obliquity? I'm going to cheat and give you an answer using moons, because many moons are are tidally locked to their planets. Io is a funny one, it's slightly eccentric orbit and proximity to Jupiter causes it to resurface pretty regularly. ...


0

The Obliquity of earth has been oscillating(approximately) with a mean period of 41,040 years. Theoretically, it has been justified that in absence of the moon, earth obliquity might become unstable. It is also a known fact that the moon is slowly moving away. By the time earth is tidally locked, the moon's effect might be significantly less, resulting in ...


0

First I think you have miss understood some basic principals. Although the Earth's speed (a scalar quantity) is nearly constant its velocity is not, acceleration is a change in velocity (a vector quantity). Due to its orbital motion the acceleration of the Earth is constantly changing. As for the actual question, the acceleration would be so small compared ...


3

If you are calculating the angular distance between planets, as viewed from Earth, then of course you need to include the retrograde motion. The natural way of doing this would be to first use heliocentric coordinates to calculate the positions of both planets and the Earth relative to the sun (You could do this using Kepler's laws). Then change your ...


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In our moving Earth-based point of view, retrograde apparent motion means a planet's geocentric ecliptic longitude is temporarily decreasing instead of increasing as usual. The word "apparent" avoids confusion with a retrograde orbit. All major planets' orbits are prograde, with heliocentric longitude increasing at all times1. Most retrograde-orbiting Solar ...


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Eyepieces The highest useful magnification of the Celestron Travel Scope 70 is about 165x. However, you are unlikely to find that much magnification to be usable except under very ideal conditions ("good seeing" i.e. clear atmospheric conditions, dark skies with no light pollution, viewing on a night with a new moon, etc). Even then the image at the ...


4

Regarding the title: Yes. Does this mean that the star started off as a planet? Yes, a star could technically start out as a planet, if it accreted enough mass. However, this is extremely unlikely, since the planet would need to be 80x the mass of Jupiter for it to undergo nucleosynthesis. Stars require hydrogen fusion and earth has little H. Could ...


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The very first stars to form indeed consisted essentially only of hydrogen and helium. When stars die, they leave behind them more massive atoms, as you say. These heavier elements are too incorporated in newer stars when they form. This results in stars which start out with a lower portion of hydrogen and helium, thus making them somewhat less effective; ...


3

A star does not start off as a planet; you have a large cloud of gas that is collapsing in on itself due to gravity. The majority of the gas goes towards creating the star (more than 99% in the case of our Solar System). However, gravitational collapses can occur several places in the gas cloud, and some of the gas will contribute towards the collapse of far ...


4

Think of when the planet is at the "side" - there's a little bit of light from the planet (ie, reflecting off the planet) shining towards us. Could it be due to that little bit of light - when the planet is behind the star, it no longer reflects towards us? Maybe that's the effect you have in mind?


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Sir Cumference's answer is great. Molecular clouds are generally thousands of times more massive than the Solar System, and since they're less dense they're much much larger in volume. We don't know where our Solar System originated from, and we don't know how many other stars were born in the same cloud, probably hundreds or even thousands (just recently 1 ...


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The same reason (almost) all of them rotate in the same direction: because of the conservation of angular momentum. Before a star and its planets exist, there’s just a cloud of disorganized gas and small molecules. The Solar System formed from such a cloud around 4.6 billion years ago. On that scale, there is some small amount of rotation within the cloud....


4

The moon has a monthly motion called libration Of interest to you is libration in latitude. The orbit isn't exactly in the plane of the ecliptic, and the rotation axis is slightly different from each. This means that about a week after passing its ascending node, you can see up to about 6.5 degrees past the moon's South pole. Two weeks later, the south pole ...


1

The formula for orbital period is $$T= 2\pi\sqrt{\frac{a^3}{G \left(M_1 + M_2\right)}}$$ For your example, $a=19000000$ metres, and $M_1 = M_2 = 6e24$ Which gives an orbital period of just over 5 hours. Whether such an arrangement is likely depends on the nature of the the formation of the binary planet, and how the orbital period and rotation rates are ...



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