Tag Info

New answers tagged

8

All stars could have their own Oort cloud, but all stars don't. As HDE says the Oort cloud was formed by material in the sun's protoplanetary disk and interstellar comets that were caught by the sun. Some theories say that almost all comets were formed around the Sun, and this wouldn't allow us to say much about comets around other stars. However there are ...


15

Awesome question, especially since we know so little of the answer. Nobody knows for sure how the Oort Cloud formed - I'll put that out there right now - but the current hypothesis is that it was originally part of the Sun's protoplanetary disk. All of the ice and rock coalesced into small bodies - proto-comets, if you will. While these bodies were much ...


3

I answered this same question at physics.SE. I specifically joined this part of the SE network to address this duplicate question at this site. The astronomy community faced two crises with regard to what constitutes a "planet", first in the mid 19th century, and more recently at the start of the 21st century. The first crisis involved the asteroids. The ...


2

There is actually disagreement on this matter (within the IAU?). Dr. Alan Stern (lead of the New Horizons mission) for instance points out that "this rule is inconsistent" (e.g. see Pluto vote 'hijacked' in revolt). Not only has Neptune not cleared its path, but the same holds for Earth, Mars and even Jupiter. Jupiter has a set of asteroids (the Trojans) ...


0

There is a much easier way to do this. 1) Look up the length of the solar year in earth days 2) multiply the length of the years like this: Mercury year * Venus year * Earth year * Martian year * Jovian year * Saturn year * Uranus year * Neptune year 3) Divide by 365 to get earth years. And you have a time when they will align again ...


1

The distance depends on the diameter of the planet and of your height above the surface (such as on a mountain). The greater the diameter, the farther away the horizon will be. You can see this in the figure below. $d_3 > d_1 > d_2$. On a large planet your horizon (at distance $d_1$) will be farther away than on a smaller planet with horizon distance ...


3

You've confused its rotation and revolution. Venus revolves around the Sun in the same way as all the other planets, but its rotation is in the opposite direction of theirs. It has retrograde rotation, but not revolution. I think this solves your paradox.


1

Pluto will continue to be exactly Pluto no matter how we choose to categorize it. Fretting about the "proper" category is the tyranny of the discontinuous mind.


3

A lot of the push to have Pluto reinstated as the 9th planet is coming from Harvard, from their press release Is Pluto a Planet? The Votes Are In (Released September, 2014), they state the following outcomes from a debate: Science historian Dr. Owen Gingerich, who chaired the IAU planet definition committee, presented the historical viewpoint. Dr. Gareth ...


6

Yes, Pluto is still a dwarf planet. According to the IAU website, it still fits the criteria for a dwarf planet, fails to meet the criteria for a planet, and still carries the "dwarf planet" label, whatever its future status may be. I'm sorry I can't provide a longer or more detailed answer, but this is really a yes-or-no question. I hope this helps.


8

According to the Case Western Reserve University webpage The Edge of the Solar System (2006) an important consideration is that The whole concept of an "edge" is somewhat inaccurate as far as the solar system is concerned, for there is no physical boundary to it - there is no wall past which there's a sign that says, "Solar System Ends Here." There are, ...


5

Here's my answer. I'll try to make it as comprehensive as possible. It's pretty hard to define the edge of the solar system. Most people would probably define it as where objects are no longer gravitationally bound to the Sun. That just shifts the question a little, though: Where is that dividing line? To try to answer this, I'll go over the regions of the ...


4

Unfortunately, the paper is not available on ArXiv (oh, what hardships we must overcome!), but I have found it here (http://www.slideshare.net/APODman2k/nature13156). In it, where the "900" figure is mentioned (2nd page, I believe), the authors (Trujillo and Sheppard) say that they ran simulations with the data already found and their additional findings, ...


0

With the volume and mass of a planet concludes are possible of its material composition. But there is more, for example auroras been observed at Jupiter. This is only possible if Jupiter has a magnetic field just like our earth. A magnetic field is a strong evidence for an iron core. The next point is, heavy materials accumulate in the center, so one could ...


3

This has been the subject of many documentaries, many of which are based on scientific observations and associated assumptions of the past in the rocks and out in space. Some are outright bizarre imaginings of people. The Discover Magazine article about this topic lists several possibilities, including the following examples that scientists have evidence of ...


3

Since I've put a lot of emotional capital into this question, I figure I might as well answer it. Empty criticism is wrong, and I would be guilty of it if I didn't explain what I mean. So here's my attempt. The Big Bang took place roughly 13.8 billion years ago, not 18 billion or 20 billion. One of the most common misconceptions (which I fell into for many ...


2

Read "Death From the Skies!" by Phil Plait. His list is quite comprehensive, going into what can kill humanity, what could destroy all life on Earth, and what could destroy the Earth itself. I don't have my copy on me at the moment, but IIRC he goes into what damage a meteor of various sizes will do. To avoid further confusion, here is a link to the book ...


2

Recent studies and simulations reported in the paper Impact-induced compositional variations on Mercury (Edgard et al. 2014), suggest that the Late Heavy Bombardment (LHB) was triggered by giant planet migration during which the main belt and E-belt are excited to higher impact velocities when resonances with the giant planets sweep across the primordial ...


2

The end of the Earth and the end of a habitat that can support life are 2 different things. The Earth will not be able to support life as we know it for 4 billion more years. The sun is slowly heating up, and estimates are that in 500 million years, the Earth will be too hot to support life. That being said, life is resilient, and who knows what ...



Top 50 recent answers are included