Physics · Science General

Astronomy and Cosmology

4,498 Questions

This topic provides questions on astronomy, cosmology, and the physical universe. It covers subjects like the Hubble sequence, constellations, dark matter, and stellar evolution. These questions help build a strong foundation for general science exam sections.

Galaxies and clustersConstellations and starsStellar evolutionSpace observatories

Astronomy and Cosmology Questions

Multiple choice

Which of these is NOT a star?

  1. Sirius

  2. Phobos

  3. Proxima Centauri

  4. the Sun
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Phobos is one of the two moons of Mars, not a star. The Sun is a star, and Sirius and Proxima Centauri are stars located outside our solar system.

Multiple choice geography environmental changes elements of weather and climate : temperature process of heat transfer in the atmosphere environmental regions (zones)

The naturally occurring bright light which is seen in the polar regions is known as __________.

  1. Aurora Borealis

  2. Aurora Australis

  3. Ultra violet radiation

  4. Both A and B
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The bright lights are a natural phenomenon found in both the northern and southern hemispheres of Polar region that can be truly awe-inspiring. Northern lights are called Aurora Borealis and southern lights are called Aurora Australis.

Multiple choice physics effects of light scattering of light and its applications some natural phenomena of light natural phenomena explained by scattering

Planets do not twinkle as stars, because :

  1. Planets are much closer to earth than stars

  2. Planets are smaller in size than stars

  3. A planet is not surrounded by gaseous atmosphere

  4. A star is not surrounded by gaseous atmosphere
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Answer is A.

Stars, except for the Sun, although they may be millions of miles in diameter, are very far away.  They appear as point sources even when viewed by telescopes.  The planets in our solar system, much smaller than stars, are closer and can be resolved as disks with a little bit of magnification. 
Since the Earth's atmosphere is turbulent, all images viewed up through it tend to 'swim.' The result of this is that sometimes a single point in object space gets mapped to two or more points in image space, and also sometimes a single point in object space does not get mapped into any point in image space.  When a star's single point in object space fails to map to at least one point in image space, the star seems to disappear temporarly.  This does not mean the star's light is lost for that moment.  It just means that it didn't get to your eye, it went somewhere else.
Since planets represent several points in object space, it is highly likely that one or more points in the planet's object space get mapped to a points in image space, and the planet's image never winks out.  Each individual ray is twinkling away as badly as any star, but when all of those individual rays are viewed together, the next effect is averaged out to something considerably steadier.
The result is that stars tend to twinkle, and planets do not.

Multiple choice physics effects of light scattering of light and its applications some natural phenomena of light natural phenomena explained by scattering

Stars twinkle but planets do not twinkle because

  1. Stars emit their own light but planets receive light from the stars

  2. Stars do not from a part of solar system

  3. Stars from a point source of light while planets are considered as a collection of a large number of point sources of light

  4. During refraction of star light from the atmosphere, star light bends more towards the normal as compared to the planets
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Light of the star is bent  many times and in random directions  as light is bent when it hits a change in density. This random refraction results in the star winking out - twinkling. 

Planets are closer to Earth and so appear  as tiny disks in our sky.
The light from these little disks is also refracted by Earth’s atmosphere, as it travels toward our eyes. Due to the planets’ apparent closeness to Earth, the light coming from these celestial bodies does not bend much due to Earth’s atmosphere. Also being not a point source but appearing as disks, they comprise of several point sources- lights of which are coming at the same time. So a deviation in light path of one point source can cancel with deviations of other and would average out to give rise to a steady shine. Therefore, the light coming from our solar system’s planets does not appear to twinkle like stars.

Multiple choice physics option d: astrophysics the big bang and the early development of the universe origin of universe evolution of the universe

The Hubble Deep Field is an image of the sky taken with a very along exposure, using the Hubble Space Telescope. Almost all of the $5000$ objects seen in that picture are?

  1. Starts that are in our own Galaxy.

  2. Dirt on the lens of the telescope.

  3. Galaxies

  4. Distant planets.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The Hubble Deep Field image was a landmark observation that revealed thousands of distant galaxies in a tiny, seemingly empty patch of the sky, demonstrating the vast scale of the universe.

Multiple choice social science option d: astrophysics the big bang and the early development of the universe origin of universe evolution of the universe

The rough estimation of visible matter in the universe is:

  1. $70\%$
  2. $80\%$
  3. $90\%$
  4. $10\%$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Dark matter can't be seen, but its presence has been revealed by observing universe. It has been estimated that more than $90\%$ of matter is invisible in universe. So, what is visible, is only $10\%$ of the universe.

Multiple choice social science universe and space the big bang and the early development of the universe origin of universe evolution of the universe

What is celestial object?

  1. Naturally occurring physical entity which exists in observable universe

  2. Artificially occurring physical entity which exists in observable universe

  3. Naturally occurring physical entity which exists in observable solar system

  4. None
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Celestial body also known as heavenly body is any naturally occurring physical object found outside the Earth's atmosphere.