Space (Physics) Part-I

Total Questions: 50

31. Black-hole is: [U.P.P.C.S. (Pre) 2019]

Correct Answer: (d) a collapsed star
Solution:

Black hole is actually a collapsed star. Black holes of stellar mass are expected to form when very massive stars collapse at the end of their life cycle. After a black hole has formed, it can continue to grow by absorbing mass from its surroundings.

By absorbing other stars and merging with other black holes, supermassive black holes of millions of solar masses may form. A black hole is a place in space where gravity pulls so much that even light cannot get out. The gravity is so strong because matter has been squeezed into a tiny space.

32. Assertion (A): Black hole is such a celestial existence which cannot be seen by telescope. [U.P.U.D.A./L.D.A. (Pre) 2001]

Reason (R): The gravitational field of black hole is much strong that even light does not escape from it.

Code:

Correct Answer: (a) Both (A) and (R) are true, and (R) is the correct explanation of (A).
Solution:

A black hole is an object which is so compact that its gravitational force is strong enough to prevent light or anything else from escaping. By this reason, one can't see it by telescope.

33. Black Hole - [Uttarakhand P.C.S. (Pre) 2007]

Correct Answer: (c) Absorbs all radiations that fall on it.
Solution:

Black Hole absorbs all radiations that fall on it due to its high gravity.

34. The tail of a comet always points- [U.P.P.C.S. (Mains) 2011]

Correct Answer: (a) Away from the Sun
Solution:

Comets are the small celestial objects made of ice, gas, dust, and a small amount of organic material that orbit our Sun. Radiation from the Sun pushes dust particles away from the coma (nebulous envelope around the nucleus of a comet), forming a dust tail, while charged particles from the Sun convert some of the comet's gases into ions, forming an ion tail.

Since comet tails are shaped by sunlight and the solar wind, they always point away from the Sun.

35. Highly dense stars are called- [Uttarakhand Lower Sub. (Pre) 2010]

Correct Answer: (b) Neutron stars
Solution:

The highly dense stars are called Neutron stars.

36. In the universe, what are pulsars? [69ᵗʰ B.P.S.C. (Pre) 2023]

Correct Answer: (b) Rotating neutron stars
Solution:

Most neutron stars are observed as pulsars. Pulsars are rotating neutron stars observed to have pulses of radiation at very regular intervals that typically range from milliseconds to seconds. Pulsars have very strong magnetic fields which funnel jets of particles out along the two magnetic poles.

37. Consider the following pairs: [I.A.S. (Pre) 2023]

Objects in SpaceDescription
1. CepheidsA. Giant clouds of dust and gas in space
2. NebulaeB. Stars which brighten and dim periodically
3. PulsarsC. Neutron stars that are formed when massive stars run out of fuel and collapse

How many of the above pairs are correctly matched?

Correct Answer: (a) Only one
Solution:

Cepheids, also called Cepheid Variables, are stars which brighten and dim periodically. This behaviour allows them to be used as cosmic yardsticks out to distances of a few tens of millions of light-years. Hence, pair 1 is not correctly matched.

Nebulae are interstellar clouds of gas and dust. Many nebulae are formed from the remnants of dying stars. Nebulae are often also regions where new stars are born. Nowadays, the term 'nebula' refers to an interstellar cloud of dust and gas. Hence, pair 2 is not correctly matched.

Pulsars are rotating neutron stars observed to have pulses of radiation at very regular intervals that typically range from milliseconds to seconds. Neutron stars are formed when massive stars run out of fuel and collapse. Most neutron stars are observed as pulsars. Hence, pair 3 is correctly matched.

38. Electrically charged particles from space travelling at speeds of several hundred km/sec can severely harm living beings if they reach the surface of the Earth. What prevents them from reaching the surface of the Earth? [I.A.S. (Pre) 2012]

Correct Answer: (a) The Earth's magnetic field diverts them towards its poles.
Solution:

Electrically charged particles from space travelling at speed of several hundred km/sec cannot reach the surface of the Earth because the Earth's magnetic field diverts them towards its poles. Its best example is "Aurora".

39. If a major solar storm (solar flare) reaches the Earth. which of the following are the possible effects on the Earth? [I.A.S. (Pre) 2022]

1. GPS and navigation systems could fail.

2. Tsunamis could occur at equatorial regions.

3. Power grids could be damaged.

4. Intense auroras could occur over much of the Earth.

5. Forest fires could take place over much of the planet.

6. Orbits of the satellites could be disturbed.

7. Shortwave radio communication of the aircraft flying over polar regions could be interrupted.

Select the correct answer using the code given below:

Correct Answer: (c) 1, 3, 4, 6 and 7 only
Solution:

Solar flares are brief and powerful eruptions of high-energy radiation from the Sun's surface, associated with sunspots. The phenomenon is known to cause radio and magnetic disturbances on Earth.

Massive solar flares can disrupt power grids, interfere with high-frequency airline and military communications, disrupt Global Positioning System signals, interrupt civilian communications, and pose risks to spacecraft and astronauts.

Solar flares could interrupt shortwave radio communication of the aircraft flying over polar regions. Solar flares can temporarily alter the upper atmosphere creating disruptions with signal transmission from, say, a GPS satellite to Earth causing it to be off by many yards.

In case of coronal mass ejection or CME, these solar explosions propel bursts of particles and electromagnetic fluctuations into Earth's atmosphere. Those fluctuations could induce electric fluctuations at ground level that could blow out transformers in power grids.

CME's particles can also collide with crucial electronics onboard a satellite and disrupt its systems. During an extreme solar flare event, the auroras (usually which are only visible in the far northern and southern polar regions) could become very intense and could be visible in places that usually never see these elusive night lights. Occurrence of tsunami and forest fires are not associated with the solar flares

40. Assertion (A): A space shuttle loses radio contact with ground station for a while during landing on the Earth. [U.P.U.D.A./L.D.A. (Pre) 2002, U.P.P.C.S. (Pre) 2003]

Reason (R): As a space shuttle enters Earth's atmosphere, the shuttle's surface temperature increases which ionize the surrounding air.

In the context of the above statements, which of the following is correct:

Correct Answer: (a) Both (A) and (R) are true, but (R) is the correct explanation of (A).
Solution:

When a spacecraft re-entered in the Earth's atmosphere, it experiences air drag creating friction. This results in an increase of shuttle's temperature and ionizes the surrounding air.

These ionized particles disturbs the radio signals and space shuttle loses radio contact with ground station for a while during landing on the Earth.