Questions tagged [astronomy]

The study of celestial objects and phenomena outside of the Earth's atmosphere.

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9
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2answers
210 views

Was science the driving force behind the Apollo program?

Was science really the driving force behind the Apollo program? Or was the "race to the moon" the primary reason and the science objectives were put together as a secondary step?
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3answers
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Who was the first to postulate that space was a vacuum?

The fact that space is a vacuum and that the Earth's atmosphere only extends a short way above the surface is accepted as obvious. However, there is nothing a priori obvious about it: you first have ...
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2answers
397 views

Why does JPL at NASA give two different values in astronomical units for planetary distances?

Why is it that JPL (Jet Propulsion Lab) at NASA gives astronomical unit values for the planets for two different time periods, namely 3000 B.C. to 3000 A.D., and 1850 to 2050?
7
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1answer
284 views

Calculation of Gauss leading to 18:7 resonance between orbits of Jupiter and Pallas

After Gauss helped relocate Ceres, he studied the orbit of the asteroid Pallas and discovered (1812) that Jupiter and Pallas have an orbital resonance that is nearly equal to 18:7. For instance, using ...
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2answers
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What attracted Einstein to the anomalous precession of Mercury?

The story is usually told starting with Einstein's 1915 paper Explanation of the Perihelion Motion of Mercury from General Relativity Theory, or at least its drafts from 1913-14. It was the first ...
3
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1answer
297 views

Planets/stars as more than points of light

Who was/were first one(s) to recognize that what we see in the night sky are not just points of lights but full blown lands(in case of moon and some planets) and so on? I am guessing it would not have ...
12
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2answers
9k views

How did ancient Greeks explain moon phases without reflection of sunlight?

Did the ancient Greeks understand that the moon shines by reflection of sunlight, and that this was the explanation of its phases? Did this allow them to conclude that the moon was a sphere? From what ...
7
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2answers
534 views

When was the issue of time zones at different longitudes first described?

What are the earliest recorded acknowledgements of the concept that motivates time zones - that the sun and other celestial objects appear in different parts of the sky to people at different ...
6
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1answer
180 views

Who created the energy conditions?

The earliest text I've been able to find that explain the GR energy conditions is "The large scale structure of space-time" (1973) by Hawking and Ellis. However in Barcelo and Visser's paper "...
15
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1answer
520 views

Why did 18th century writers think that Mars had 2 satellites?

At least two 18th century writers wrote that Mars has two satellites: Swift in Gulliver's travels (1726) and Voltaire in Micromégas (1752). How did they guess this? Was Voltaire repeating Swift's ...
5
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1answer
469 views

When was the first true Gregorian telescope built?

I know that James Gregory came up with the idea of using a parabolic mirror to eliminate spherical aberration in 1663. The theory behind it had actually been around since classical antiquity I think....
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3answers
6k views

When did humans realize that there is no air on the Moon?

What is the easiest evidence that there is no air on the Moon? Frankly speaking, I myself have no idea how to prove it.
6
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1answer
329 views

Hevelius-Hooke dispute

Johannes Hevelius of Danzig (1611-1687) was the most famous astronomer of his time, and also the last famous astronomer who did not use telescope. Most books on the history of astronomy (and even the ...
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74 views

Who found out about galaxies? [closed]

As the world developed new technology, astronomers discovered more celestial bodies, such as asteroids and black holes and such. Galaxies were probably discovered long ago before these modern ...
12
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3answers
6k views

Why didn't Aristarchus' theory of Heliocentrism stick?

This might be more a question for historians, but it's a question I've given some thought to. By using what was essentially Euclidean geometry, Aristarchus was able to calculate, with some measure ...
6
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3answers
381 views

Who was the first person to use physics to suggest that both the Sun and the Earth move?

I imagine it to be Isaac Newton, who brought the discussion of "force" rather than "center" into the modeling of orbits. I imagine that prior to Newton's forces, one had to be either a geocentrist or ...
18
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3answers
2k views

How did Kepler "guess" his third law from data?

It is amazing that Kepler determined his three laws by looking at data, without a calculator and using only pen and paper. It is conceivable how he proved his laws described the data after he had ...
6
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2answers
173 views

Did Schiaparelli comment on the martian canals debate?

It s well known that in 1888, Italian Giovanni Schiaparelli announced finding a network of narrow lines on Mars, which he described as "canali," which a lot of English speakers including American ...
2
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0answers
897 views

Was Kepler aware of the following golden relationship between the planets?

Was Kepler aware that Venus and Mars have a golden section relationship other than that he attributed to them in his 5 perfect solids model of the Solar System? The dodecahedron and the icosahedron, ...
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3answers
3k views

How long did it take to prove that the Earth revolves around the Sun?

I get that Galileo Galilei was a major contributor in proving the helio-centric theory, and same goes to Sir Isaac Newton. The battle for the theory to become law took centuries to prove. People ...
11
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3answers
3k views

Who first distinguished planets from the stars?

This is a pretty straightforward question, when the first observations of the night sky were being made, who was the first person to suggest that a planet, say Mars, was not a star, in the sense that ...
20
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3answers
10k views

Who first measured the distance to the Moon? How was it done?

Who first measured the distance to the Moon? How was it done? I think it had to happen after Newton, but I am not sure.
15
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1answer
3k views

How did Babylonians figure out that the evening star is the morning star?

Hesperus (Roman Vesper) is the name ancient Greeks gave to the evening star that appears in the sky for an hour after the Sun sets. Phosphorus (Roman Lucifer, sic!), was the name of the morning star ...
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3answers
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Why should February have 28 days?

According to the Gregorian calendar the second month i.e. February have 28 days and in a leap year 29 days. I am not sure what calculations(science) it takes to decide the total number of days in ...
7
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1answer
158 views

When did the idea of naming asteroids after humans come about?

There are some trends to naming celestial objects: Planets and moons in the solar system may be named after ancient Greek and Roman gods Comets may be named after their discoverer Asteroids may be ...
18
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1answer
480 views

Did Archimedes use epicycles in his planetarium?

Archimedes constructed a planetarium where as described by Cicero "he had thought out a way to represent accurately by a single device for turning the globe those various and divergent movements with ...
6
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1answer
330 views

When was the airless void above the earth discovered?

For a very long time, people had no reason to believe that an airless void could exist in nature at all, whether above the earth or anywhere else. According to Descartes, in his 1633 work The World, ...
6
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1answer
760 views

Who discovered the "Comet" as a celestial object?

Who first discovered that comets were physical objects with a Keplerian orbit? Was this accidentally discovered or was it discovered as part of an intentional effort by astronomers after they ...
24
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5answers
7k views

Is there an astronomical reason behind the order for the names of days of the week?

The seven days of the week seems to be commonly named after celestial bodies. What I find curious is that all seven days apparently share the same names in both West and East. Sunday is, of course, ...
22
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2answers
5k views

When did it become possible to predict the time and place of solar eclipses?

That is, when did astronomy figure out how to predict when and where a solar eclipse will be visible? It seems people noticed fairly early on that the Sun, Moon and Earth return to the same ...
19
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1answer
774 views

Before 1964, did scientists generally believe there was life on Mars?

Mariner 4 was the first spacecraft to return photographs of Mars from near the planet, making its flyby of Mars in 1964. Those photographs showed what appeared to be a barren, desert surface. ...
12
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1answer
381 views

Division of the circle and compass constructions

It is well known that every construction that can be performed by a compass and a ruler can be also performed by a compass only. This is a good (and difficult) exercise in elementary geometry. My ...
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2answers
481 views

What happened in astronomy between Hipparchus and Ptolemy?

Hipparchus applied Apollonius's epicycle/eccenter construction to the motion of the Sun and the Moon, but not to the planets. There are speculations about epicyclic gears for planets in the ...
20
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1answer
454 views

When & how was it known that our Sun is the same thing as the night time stars?

Who was the first person to conjecture that our Sun is just another star? Relatedly, what was the first evidence that this was true?
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2answers
416 views

What data did Kepler work out his laws from?

It's well known that Kepler worked out his laws by fitting curves to Tycho Brahe's data on the trajectories of planets through the sky. What was this data? How does one record the trajectory of a ...

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