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Common misconceptions about astronomy

When object rotates around something with mass M its speed calculated by this formula (simplified way):

58e6d3db5594ffc9650a819d33baab00.png


R - orbit radius, G - gravitation constant. Thus the higher is Mass of central object the higher is rotation speed. This formula predicts very well speeds of planets around the Sun, or speeds of moons around planets, satellite speeds etc etc...

But when astronomers checked speeds of stars rotating around galaxies they noticed that speeds are much higher than this formula shows. And its not just one star in one galaxy, but all stars in all galaxies have same problem.

There are two possible solutions to this problem:

1) Propose there is some additional mass in galaxies which we can't see (called Dark Matter theory).
2) Propose that formula at very big ranges and masses is wrong and should be modified (MOND theory).

https://en.wikipedia.org/wiki/Dark_matter
https://en.wikipedia.org/wiki/Modified_Newtonian_dynamics

Dark Matter currently is much more accepted theory than MOND. It gives better predictions and has much less problems. However all attempts to detect these unseen particles which create the Dark Matter so far have failed. That means Dark Matter remains only a theory. So I'll add a misconception:

33) Dark Matter is not a fact.
1)how anti matter works and how efficient can it be as fuel for space ships
2)will we ever be able to travel faster then light.
3)is there any way we travel back in time
 
1)how anti matter works and how efficient can it be as fuel for space ships
2)will we ever be able to travel faster then light.
3)is there any way we travel back in time
Hello.

1) Anti matter-matter annihilation is most effective source of energy: 100% of mass converts to energy. There are two major problems however: first u need to produce anti matter which is supper expensive: NASA estimated cost of one gram of antimatter as 62 trillion $. Second problem that storing anti matter is also very problematic since it annihilates when touches a regular matter, even air. So not in our lifetime for sure.

2-3) Are actually connected to each other, coz both break reason-cause connections (u can go in past and kill ur grandfather). I really doubt it will be ever possible. The most common solution is creating wormholes. But no one even remotely knows how to create them and in order to stabilize them we would need matter with negative mass and other exotic stuff which no one ever seen and very doubtful it is even exists at all.
 
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you do really need an anti-matter annihilator to power up your next generation merkava tho
 
1) The Big Bang was a huge explosion.

When people are told about a Big Bang they are imagining something like this:

Big%20Bang.jpg


However the Big Bang was not an explosion in space like in this pic, it was a rapid expansion of space itself. Thus it does not have any center and we cant actually imagine it.

2) Universe is a sphere with ~13 bln light year radius.

Its linked to previous point. We know that universe is ~13 bln years old. Thus many people think that its expanded from the bing bang to a sphere with 13 bln light years diameter. But as I noted it was not an explosion. U cant show a point in universe where the Big Bang happened. Simply the space between the galaxies is expanding. Thus the more far is a galaxy the faster it is moving away from us and there is no speed limit. Very distant galaxies are moving from us faster than light! No one knows the actual size of the universe and its shape. We only know its much much larger than sphere with13 bln light years radius, maybe its infinite.

3) Nebulas are dense clouds in space.

In sci fi nebulas usualy look like this, you can hide ur spacecraft inside:

View attachment 287289

In fact the density of nebulas is extremely low: most dense one have only about 10,000 atoms per cm3. For comparison space at LEO orbit where most satellites are flying has MILLIONS atoms per cm3. From close range u wont see a nebula at all.

4) Flying through asteroid belt is very dangerous.

This misconception is similar to above. Flying through asteroid belt looks like this in sci fi:

latest


Although there are billions of asteroids in asteroid belt, the space is so huge that the average distance between two asteroid is hundreds of thousands km.

5) The asteroid belt might be an exploded planet.

The total weight of asteroid belt is less than 1/2000 of earth's. If u merge all asteroids together they will form a tiny moon, much smaller than our own.

6) Black holes are like giant vacuum cleaners which suck everything around them.

In order to notice the gravitational difference between the black hole and star of same mass u need to come very very close (to star radius). Thus is sun magically collapses into a black hole we wont notice any difference except the lack of light and heat. The orbit will remain the same.

7) Our galaxy rotates because of a giant black hole in its center.

In the center of our galaxy there is indeed a supermassive black hole with mass of 4 million sun. But the milky way galaxy has mass of over trillion suns. If u remove a black hole from our galaxy it will keep rotating as before. Supermassive black hole does not affect the galaxy rotation at all.

8) The moon color is yellow/whitish.


The albedo (reflection rate) of the moon in visual light is only 7%. That's very dark grey close to black. The moon seems bright only compare to black space. If moon was yellow it would be many times brighter.

9) The Sun is yellow.

The sun emits all spectrum of colors, but the peak lies in green! But our eye sees it as clear white in space. And on earth because of atmosphere it seems yellowish to our eyes.

10) Our Sun is very small star.

Although there are stars much much bigger than our sun, the average size of stars in universe is much smaller than our sun.

11) Winter is colder because the orbit is oval and we are further from the sun then.

Winters are colder because of inclination of the earth. In fact in Northern hemisphere we are actually closer to the sun in winters.

=================

You can add other misconceptions u know.
I never knew about ATRONOMY before!

1) The Big Bang was a huge explosion.

When people are told about a Big Bang they are imagining something like this:

Big%20Bang.jpg


However the Big Bang was not an explosion in space like in this pic, it was a rapid expansion of space itself. Thus it does not have any center and we cant actually imagine it.

2) Universe is a sphere with ~13 bln light year radius.

Its linked to previous point. We know that universe is ~13 bln years old. Thus many people think that its expanded from the bing bang to a sphere with 13 bln light years diameter. But as I noted it was not an explosion. U cant show a point in universe where the Big Bang happened. Simply the space between the galaxies is expanding. Thus the more far is a galaxy the faster it is moving away from us and there is no speed limit. Very distant galaxies are moving from us faster than light! No one knows the actual size of the universe and its shape. We only know its much much larger than sphere with13 bln light years radius, maybe its infinite.

3) Nebulas are dense clouds in space.

In sci fi nebulas usualy look like this, you can hide ur spacecraft inside:

View attachment 287289

In fact the density of nebulas is extremely low: most dense one have only about 10,000 atoms per cm3. For comparison space at LEO orbit where most satellites are flying has MILLIONS atoms per cm3. From close range u wont see a nebula at all.

4) Flying through asteroid belt is very dangerous.

This misconception is similar to above. Flying through asteroid belt looks like this in sci fi:

latest


Although there are billions of asteroids in asteroid belt, the space is so huge that the average distance between two asteroid is hundreds of thousands km.

5) The asteroid belt might be an exploded planet.

The total weight of asteroid belt is less than 1/2000 of earth's. If u merge all asteroids together they will form a tiny moon, much smaller than our own.

6) Black holes are like giant vacuum cleaners which suck everything around them.

In order to notice the gravitational difference between the black hole and star of same mass u need to come very very close (to star radius). Thus is sun magically collapses into a black hole we wont notice any difference except the lack of light and heat. The orbit will remain the same.

7) Our galaxy rotates because of a giant black hole in its center.

In the center of our galaxy there is indeed a supermassive black hole with mass of 4 million sun. But the milky way galaxy has mass of over trillion suns. If u remove a black hole from our galaxy it will keep rotating as before. Supermassive black hole does not affect the galaxy rotation at all.

8) The moon color is yellow/whitish.


The albedo (reflection rate) of the moon in visual light is only 7%. That's very dark grey close to black. The moon seems bright only compare to black space. If moon was yellow it would be many times brighter.

9) The Sun is yellow.

The sun emits all spectrum of colors, but the peak lies in green! But our eye sees it as clear white in space. And on earth because of atmosphere it seems yellowish to our eyes.

10) Our Sun is very small star.

Although there are stars much much bigger than our sun, the average size of stars in universe is much smaller than our sun.

11) Winter is colder because the orbit is oval and we are further from the sun then.

Winters are colder because of inclination of the earth. In fact in Northern hemisphere we are actually closer to the sun in winters.

=================

You can add other misconceptions u know.
You every now and then come up with very good things.:tup:
 
By the way, light speed question made me think of another misconception. Its not really astronomic but connected to it.

34) Nothing can travel faster than light.

When we say "nothing can travel faster than light" we forget to add "speed of light in vacuum", which is about 300,000 km/s.

Speed of light in some medium (like gasses, glass, water) is lower than speed of light in vacuum however. For example speed of light in water is only 225,000 km/s. So in water some particles, for example electrons can travel faster than light! When electron moves through medium faster than speed of light in creates bluish light called Cherenkov's light:


This effect is used in astronomy to detect neutrinos.
 
31) Supernova explosion is one of the most luminous events in Universe.

While Supernova explosion produces insane amounts of energy, most it goes to kinetic expansion of outer star layers and only a small portion into electromagnetic radiation (light). Supernova reaches the peak of its luminosity only weeks after the explosion as result of Ni56 nuclear fission (Type I supernova) or Hydrogen recombination (Type II supernova). Only then it becomes one of the most luminous events in universe.


Persian Philosophers Text Describes A Supernova In 1006 AD

http://sciencenewsjournal.com/persian-philosophers-text-describes-supernova-1006-ad/


Hello.

1) Anti matter-matter annihilation is most effective source of energy: 100% of mass converts to energy. There are two major problems however: first u need to produce anti matter which is supper expensive: NASA estimated cost of one gram of antimatter as 62 trillion $. Second problem that storing anti matter is also very problematic since it annihilates when touches a regular matter, even air. So not in our lifetime for sure.

2-3) Are actually connected to each other, coz both break reason-cause connections (u can go in past and kill ur grandfather). I really doubt it will be ever possible. The most common solution is creating wormholes. But no one even remotely knows how to create them and in order to stabilize them we would need matter with negative mass and other exotic stuff which no one ever seen and very doubtful it is even exists at all.


Well in a way time travel exist in the universe right ? What ever galaxies or events we are seeing in the universe has happened million of years ago and probably doesnot exist right now and it is just that their light light reaches to us we are able to observe their original state. Good example of this is this thing

http://sploid.gizmodo.com/it-sounds-incredible-but-the-pillars-of-creation-dont-e-1677857108

Quantum entanglement is one area if successfully cracked and implemented will make our communication speed faster than speed of light.

and to move faster than light only if the existence of tachyons are proved

https://en.wikipedia.org/wiki/Tachyon
 
Well in a way time travel exist in the universe right ? What ever galaxies or events we are seeing in the universe has happened million of years ago and probably doesnot exist right now and it is just that their light light reaches to us we are able to observe their original state. Good example of this is this thing
EVERYTHING we see is in past. Near objects are nanoseconds in past, Moon is 1.5 seconds in past, Sun - 8 minutes in past, stars u see with naked eye are up to 1000 years in past.

Quantum entanglement is one area if successfully cracked and implemented will make our communication speed faster than speed of light.
You cant use quantum entanglement to send information, because once u try to get information u destroy quantum entanglement.
and to move faster than light only if the existence of tachyons are proved

https://en.wikipedia.org/wiki/Tachyon
Its hypothetical only.
 
EVERYTHING we see is in past. Near objects are nanoseconds in past, Moon is 1.5 seconds in past, Sun - 8 minutes in past, stars u see with naked eye are up to 1000 years in past.


You cant use quantum entanglement to send information, because once u try to get information u destroy quantum entanglement.

Its hypothetical only.
A very interesting thread. Im inspired by ur knowledge on the subject. However, i have a question:
What is the physical possibility of 7 heavens? Do they exist in this visible universe or in other dimensions or maybe they occur when we cross speed of light? Or parallel universes?
 
A very interesting thread. Im inspired by ur knowledge on the subject. However, i have a question:
What is the physical possibility of 7 heavens? Do they exist in this visible universe or in other dimensions or maybe they occur when we cross speed of light? Or parallel universes?
Hello. There is no such thing as "heaven" in astronomy or in science,

35) Electrons in atom are like planets in Solar system:

planetary-model.png


Electrons in atom are following completely different laws than planets in Solar system. Here two major differences:
1) Electrons can be only on specific orbits, they can never be in between these orbits. Electron disappears on one orbit and appears on another.
2) The "orbits" of electrons are completely different from the orbits of planets. We can never know where exactly electron is located in any given moment but only a probability. Its like randomly jumping around the atom core:

bvMeZklh51o.jpg
 
Hello. There is no such thing as "heaven" in astronomy or in science,

35) Electrons in atom are like planets in Solar system:

planetary-model.png


Electrons in atom are following completely different laws than planets in Solar system. Here two major differences:
1) Electrons can be only on specific orbits, they can never be in between these orbits. Electron disappears on one orbit and appears on another.
2) The "orbits" of electrons are completely different from the orbits of planets. We can never know where exactly electron is located in any given moment but only a probability. Its like randomly jumping around the atom core:

bvMeZklh51o.jpg
is it possible that we are building block of some thing bigger like atoms are
or is it possible that there are some miniature life form on some atoms
just fantasizing
 
is it possible that we are building block of some thing bigger like atoms are
or is it possible that there are some miniature life form on some atoms
just fantasizing
No its not possible. As I mentioned laws in atoms are completely different from laws in our world. Also each elementary particle is exactly same, while each planet and star is different.
 
36) Neutron stars are made of neutrons.

Neutron stars are so dense objects that we have no physical model to describe them with certain. We can only suppose.

There are 6 major models of Neutron stars:

a) Classic Neutron star. It consists of Hydrogen-Helium atmosphere, Iron crust and under it Neutron-Proton-Electron-Muon combination. Ratio of neutrons is growing towards the center up to 10 to 1 (10 Neutrons vs 1 Proton).
b) Pion condencate star. As above but has negative Pion core.
c) Nucleon star. As a) but with negative Kaon core.
d) Hyperon star. As a) but with Hyperon core.
e) Quark-Hybrid star. As a) but with Quark core.
f) Quark star. Under the Hydrogen-Helium atmosphere and Iron crust all made of quarks.

We dont know which model of Neutron star is correct. Maybe there is a combination depending on its mass.
 
I will post here some interesting FACTS now (as I think):

1) Luminosity of the star is proportional to power 4 of its mass. Means if star is 5 times heavier than our Sun it's luminosity will be about 5^4 = 625 times more!

2) Lifespan of the star is inversely proportional to cube of its mass. Means if star is 5 times bigger than our Sun its life span will be 5^3= 125 times less. Since lifespan of the Sun is about 10 bln years means it will be about 80 mln years.

On the other hand if star is 5 times smaller than our Sun (i.e. red dwarf) it will live 125 times longer = 1,250 billion years!

3) Since our universe is "only" 14 billion years old and red dwarf can live over trillion years, none of the red dwarf formed in the beginning of the universe has not died yet, they are still very very young (about 1 year old in human years).

4) We cant see a single red dwarf star with naked eye, although they are wast majority of total stars in our galaxy (up to 80%).

5) The number of stars between arms of spiral galaxy is similar to number of stars in arms:

gabany_m51_sn2011.jpg


The reason why arms look bright is because they contain lots of large very luminous short living blue giants.
 

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