Questions tagged [solar-system]

Questions regarding the Sun and objects orbiting it.

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10
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2answers
187 views

How did we first determine the Earth's departure from sphericity?

I'm quite interested to know the history of the study of the Earth's departure from spherical symmetry. What were the first methods used to model the non-spherical geometry of the Earth? For example, ...
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0answers
63 views

Earth shape and rotation

Imagine a helicopter that took off from point A and goes vertically in the air to a certain fixed point B in the atmospheric area at a certain fixed altitude with enough fuel to stay there (at point ...
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1answer
1k views

What is the reason the Jovian planets are in descending order of size?

Is there any scientific reason for the jovian planets to be in descending order of size or is it purely coincidental? In terms of radii it goes Jupiter, Saturn, Uranus and Neptune.
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1answer
294 views

The most feasible hypothesis about Theia

The formation of the Moon had many hypothesis over the years, most of them involving a Mars-sized body called Theia, which presumably collided with the Earth. But even within the Theia hypothesis, is ...
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1answer
111 views

How have we measured the radius of the Earth (old and new)?

I'd imagine ancient methods are fun exercises in geometry. how has the measurement has evolved over time? The first method is credited to Eratosthenes. He knew that during the summer solstice in ...
2
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1answer
98 views

Reference frames in relativity?

I've recently been introduced to relativistic celestial Reference Systems (RS) such as the Geocentric Celestial Reference System (GCRS) and Barycentric Celestial Reference Systems (BCRS). So, for ...
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2answers
159 views

If gaseous planets have solid core, can they theoretically be considered as rocky planets?

I read that gaseous planets such as Jupiter and Saturn, have a solid core deep inside. So, I wondered whats the difference between them and rocky planets apart from the fact that they have - what can ...
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1answer
142 views

If the Oort cloud has billions of objects larger than 20 km, then why do we have so few comets?

According to Wikipedia: “The Oort cloud may have billions of objects with absolute magnitude brighter than 11 (corresponding to approximately 20-kilometre diameter)”
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4answers
1k views

How do we not know what's in the Solar System? [duplicate]

It seems every once in a while there's a claim of a new planet in the Solar System. I don't understand how local planets can stay undiscovered for this long when astronomers are accomplishing what ...
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2answers
2k views

How far could be an object from the Sun and still be under the influence of its gravitational field?

I'm trying to see how far can our star reaches with its gravity. I'm asking if anyone could give info as to what's our star's limit or the furthest object found in our solar system.
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2answers
427 views

Was there ever a hypothesis about a planet called Biga?

I just re-read a popular astronomy book that was published when I was a child, about 1973. It starts with an interview to Harold C. Urey where the interviewer asks about a hypothetical planet in our ...
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1answer
73 views

Are there more images with different filters available for the April 6 Hubble image of Jupiter?

This recent HST image of Jupiter near opposition is described here and here and was made under HST proposal 14756. It was taken with WFC3/UVIS. It is made from three images using narrow-band filters ...
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0answers
57 views

Why do most galaxies or planetary systems have disc shape? [duplicate]

If we assume that mass was initially uniformly distributed in an area, then why does it flatten out after long time? For example, consider our solar system or most galaxies out there.
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3answers
667 views

Are the planets Trappist-1 in the solar system?

I'm an Astronomy noob, but I'm interested in learning how stars and planets work. Everything started with the Trappist-1. I read about it, and it's fascinating. However, it's impossible for me to ...
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2answers
141 views

JPL DE Documentation

I'm currently trying to write a C++ library that makes accessing binary data from a JPL ephemeris file easier. So far I sifted through the web, trying to find a good and thorough documentation about ...
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2answers
1k views

What are the other examples of medium-sized stars? [closed]

Please put the light year also. Its for our report so I need some examples. I've already searched on some books but I don't find anything.
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1answer
90 views

Is the centre of axial precession perfectly perpendicular to the ecliptic?

It is my understanding that the Earth's axial precession is such that the direction of the North pole pointing to the celestial sphere traces out a circle with a period of roughly 26,000 years. My ...
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2answers
294 views

Do astronomers generally agree that the distinction between comets and astroids is not so clear?

edit: I just saw this tweet and find it incredibly relevant :) begin question: First see this answer and then consider if there are known, or likely to be identified cases of solar system bodies that ...
4
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1answer
334 views

Is there a prediction when our solar system would fall apart?

Within a few billion years our Sun would become a red giant and destroying Mercury and Venus and perhaps even the Earth. But nevertheless our solar system still have some planets like Jupiter and ...
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1answer
134 views

How can 16 Psyche be the core of a protoplanet?

The recent approval of a NASA mission to study the asteroid 16 Psyche brought to my attention that Psyche (about 200 km in diameter) is thought to be the exposed iron core left over from a protoplanet ...
5
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1answer
98 views

How would a celestial map for Callisto depict the paths of Jupiter, the Sun, etc.?

Let's say we're mapping Callisto's northern celestial hemisphere in a way similar to this map of Earth's. Along with the stars (which let's just ignore for this question), this map will identify the ...
8
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1answer
272 views

Which celestial object in the solar system has the fastest tangential velocity at its surface?

Consider all of the naturally-occurring objects in the solar system : in the reference frame of the object's center (ie, ignoring the orbital velocity around the sun or, in the case of satellites, ...
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2answers
4k views

How did they decide the length of one year even though it wasn't known that earth revolves around the sun?

It takes one year for the earth to go around the sun, but one year was already this long when they didn't even know that the earth revolves around the sun at all. So how did they figure it out?
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1answer
544 views

Is the galaxy made of a nebula or the solar system?

My book says on the topic 'Formation of stars' that a galaxy starts forming by the accumulation of hydrogen gas in the form of very large clouds called nebulae. Then local lumps of gas are formed. ...
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1answer
105 views

Understanding the theory of an expanding Universe

How did Edwin Hubble determine the Universe was expanding? Was he looking in a particular direction? And where does this Galaxy sit in the expansion.
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0answers
542 views

How to calculate the orbits of Neptune and Pluto based on the orbits of Uranus and Neptune respectively?

I get the below from Neptune and Pluto. In 1821, Alexis Bouvard published astronomical tables of the orbit of Neptune's neighbour Uranus.[22] Subsequent observations revealed substantial deviations ...
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1answer
112 views

If a star orbited another star, how would that affect parallax measurements of the other star from the vantage point of the first?

Example: If hypothetically, the vantage point would move 2AU along an orbit around the star being measured, would that make it seem as if the other star moved twice the distance over the back-drop?
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1answer
230 views

How to calculate planetary position over vast time spans

Ignoring the turbulent beginnings of our solar system I wonder if there is a meaningful way to calculate the relative position of the planets of our solar system 100 million years into the future ...
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1answer
550 views

“Official” time for other planets

I want to make clock that shows current time on different solar bodies. For that I need to know how to count time on those planets. Is there any official definition of times on other planets in our ...
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2answers
1k views

What is direction of Sun's axis of rotation relative to the Earth's orbital plane around the Sun?

The present northern direction to the nearest 0.5 degrees with degree zero being the start of January and measured counterclockwise (same as Earth's orbit relative to celestial north pole). If the ...
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1answer
374 views

Period of unique horoscopes?

What is the period of unique horoscopes? In other words how long does it take before any configuration of the classical planets repeats? The seven classical "wandering stars" are: Sun, Moon, Saturn, ...
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2answers
1k views

How can clouds form in Jupiter's atmosphere of Hydrogen and Helium?

Here is a graphic of cloud layers of Jupiter (source: Wikipedia): There are three distinct cloud layers of ammonia, ammonium hydrosulfide, and water. The temperature and pressure conditions seem to ...
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3answers
180 views

What can the average Astronomy Enthusiast do to learn more [closed]

Maybe this sounds like a silly question (and hopefully is legitimate), but I will elaborate a little more. I seem to love astronomy, every single thing about it, I find it brilliant, interesting, ...
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1answer
81 views

Are the “extinct species” of meteorites originally from the “Barbarian” asteroids?

I've asked earlierin this unanswered question about an "extinct species" of meteorite, now I've just read in Phys.org about Barbarian asteroids: Named after the first asteroid of this type ...
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1answer
122 views

Which kind of strategy should we take to discover Planet 9 and other KBOs?

What are the differences between the discoveries of Sedna, 2012vp 113, and the supposed Planet 9? All need deep infrared surveys at the ecliptic plane, but P9 needs a much deeper survey?
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1answer
938 views

'Very High Noon' - Sun directly overhead

Twice a year the sun is at a certain angle south (or north) of the equator between The Tropic of Cancer and The Tropic of Capricorn. At that time the sun will be exactly overhead for people at the ...
2
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1answer
625 views

Orbital elements of solar system using Pyephem

I'm using the astrometric python module Pyephem, and I would like to get the orbital (keplerian) elements for the solar system planets. The only values I found is the heliocentric latitude, ...
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1answer
2k views

How to calculate the current distance between two planets [duplicate]

I'd like to add a feature to one of my apps that calculates the current distance between the Earth and Mars (or any other planet, for that matter). My google searches have led me to statistics of ...
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2answers
176 views

Explaining the Drake Equation on a smaller scale

So me and my friend were planning a video to explain the Drake Equation (within a time limit of 5 minutes), and we needed some help. This video is aimed at explaining the concept to an age group ...
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1answer
430 views

Effects of the solar tide on planets

It’s well known that (lunar) tides on Earth result in a transfer of angular momentum from Earth proper to the Earth–Moon orbital motion. That’s why the Moon resides now in a high Earth orbit, and ...
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1answer
52 views

Observations of a perigee coincident with a full Moon

Hopefully this will be a quick and easy question, with a quick and easy answer, but why is it that we observe a perigee Moon coincident with a full Moon approximately every 13 months? Is this related ...
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2answers
406 views

Why are some universal entities round and others are flat?

I've been wondering for a while now why some objects in the universe (such as stars, planets, etc.) are round, while others are flat (galaxies, planetary rings and protoplanetary disks). I know these ...
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5answers
18k views

Is the Sun in our solar system moving or stationary?

When I was small, I read that Sun is fixed at the center of the solar system and that all the other planets rotate around it. But later I heard that even the Sun is not fixed; it moves. Is this true? ...
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2answers
624 views

How many judges sat on Galileo's trial over heliocentrism and who were they exactly?

I saw several chronologies of the trial online but most of them only mention the name of Urban 8 as involved in the actual court proceedings. How many judges were involved and who were they exactly? ...
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0answers
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Are the Voyager spacecraft outside of our Solar System? [duplicate]

The wikipedia says that Voyager 1 cross the heliosphere, but is really outside the Solar System, or need to cross the Oort cloud?
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1answer
221 views

A question about the distribution of mass among the planets in the Solar System

Is it coïncidence that the mass of a planet has about its maximum in the middle planets (Jupiter), while the mass of the closest and furthest planets has a minimum (Mercury and Pluto)?
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1answer
431 views

Can stars be seen in the background when looking directly at our solar system?

Imagine viewing the solar system from the outside: Considering the sun is quite bright, would you still be able to see stars in the background, or does the sunlight disable us to do so? Consider ...
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2answers
799 views

Will Saturn's Moons be destroyed?

I heard that Saturn has 62 moons with confirmed orbits, 53 of which have names and only 13 of which have diameters larger than 50 kilometers. Some come within 1km of each other. How do these moons ...
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4answers
529 views

What are the exact causes that differences in sunrises are shorter around june and december but long in march and september?

The changes of the sunrise and sunset times not expire regularly in a straight line but according to a sinusoid. Around the solstice (summer solstice on June 21st and winter solstice on December 21), ...
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2answers
157 views

Does the retrograde movement affect the true angular distance between 2 planets?

I need to calculate the relative angular path between two planets in the geocentric view or in other words the number of degrees of a circle one planet travels away from another planet around the ...

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