Space Part-1

Total Questions: 50

1. Highly dense stars are called: [Uttarakhand Lower Sub. (Pre) 2010]

(a) Supernova
(b) Neutron stars
(c) Binary stars
(d) Asteroid

Correct Answer: (b) Neutron stars

Solution:The highly dense stars are called Neutron stars.

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

(a) A group of stars
(b) Rotating neutron stars
(c) Explosion of a star
(d) Radio waves emitted by a star

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.

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

Objects in space — Description

Cepheids — Giant clouds of dust and gas in space
Nebulae — Stars which brighten and dim periodically
Pulsars — Neutron stars that are formed when massive stars run out of fuel and collapse

How many of the above pairs are correctly matched?

(a) Only one
(b) Only two
(c) All three
(d) None

Correct Answer: (a) Only one

Solution:

Cepheids — Giant clouds of dust and gas in space: This is incorrect. Cepheids are a type of star that pulsates radially, meaning their brightness varies periodically.

Nebulae — Stars which brighten and dim periodically: This is incorrect. Nebulae are giant clouds of dust and gas in space. They can be regions of star formation or the remnants of dead stars. The brightening and dimming characteristic belongs to variable stars like Cepheids.

Pulsars — Neutron stars that are formed when massive stars run out of fuel and collapse: This is correct. Pulsars are indeed rapidly rotating neutron stars that emit beams of electromagnetic radiation. These beams sweep across space, and if one passes Earth, we detect it as a pulse. They are formed from the collapsed cores of massive stars after a supernova explosion.

Therefore, only one of the pairs is correctly matched.

4. 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]

(a) The Earth’s magnetic field diverts them towards its poles.
(b) Ozone layer around the Earth reflects them back to outer space.
(c) Moisture in the upper layers of atmosphere prevents them from reaching the surface of the Earth.
(d) None of the statements (a), (b), and (c) given above is correct.

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

Solution:Electrically charged particles from space traveling at speeds 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."

5. 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]

GPS and navigation systems could fail.
Tsunamis could occur at equatorial regions.
Power grids could be damaged.
Intense auroras could occur over much of the Earth.
Forest fires could take place over much of the planet.
Orbits of the satellites could be disturbed.
Shortwave radio communication of the aircraft flying over polar regions could be interrupted.

Select the correct answer using the code given below:

(a) 1, 2, 4, and 5 only
(b) 2, 3, 5, 6, and 7 only
(c) 1, 3, 4, 6, and 7 only
(d) 1, 2, 3, 4, 5, 6, and 7

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

Solution:

GPS and navigation systems could fail. (True) Solar flares emit intense electromagnetic radiation that can disrupt the ionosphere, the layer of Earth's atmosphere that GPS signals pass through. This disruption can cause inaccuracies or complete failure of GPS and other satellite-based navigation systems.
Tsunamis could occur at equatorial regions. (False) Tsunamis are primarily caused by underwater earthquakes, volcanic eruptions, or landslides. Solar storms do not have a direct mechanism to trigger these events.
Power grids could be damaged. (True) Geomagnetically induced currents (GICs) generated by solar storms can flow through long conductors like power lines, potentially overloading transformers and causing blackouts. This has happened in the past, such as the Quebec blackout in 1989.
Intense auroras could occur over much of the Earth. (True) Solar storms increase the flux of charged particles entering Earth's magnetosphere. These particles interact with the atmosphere, especially near the poles, causing the spectacular light displays known as auroras. During very strong storms, auroras can be visible at much lower latitudes than usual.
Forest fires could take place over much of the planet. (False) There is no direct scientific evidence linking solar flares to an increased risk of widespread forest fires. While solar radiation affects Earth's atmosphere and climate, it doesn't create a direct ignition source for widespread fires.
Orbits of the satellites could be disturbed. (True) The increased energy and particles from a solar storm can heat and expand Earth's upper atmosphere. This expansion increases the drag on satellites, especially those in low Earth orbit, potentially altering their orbits and even causing them to lose altitude.
Shortwave radio communication of the aircraft flying over polar regions could be interrupted. (True) The ionosphere, which is affected by solar flares, is crucial for the reflection of shortwave radio signals used in long-distance communication, including that with aircraft, especially over polar regions. Disruptions to the ionosphere during a solar storm can lead to blackouts or interference in these communications.

Therefore, the possible effects of a major solar storm reaching Earth include 1, 3, 4, 6, and 7.

The correct answer is (c) 1, 3, 4, 6, and 7 only.

6. The terms 'Event Horizon', 'Singularity', 'String Theory' and 'Standard Model' are sometimes seen in the news in the context of: [I.A.S. (Pre) 2017]

(a) Observation and understanding of the Universe.
(b) Study of the solar and the lunar eclipses.
(c) Placing satellites in the orbit of the Earth.
(d) Origin and evolution of living organisms on the Earth.

Correct Answer: (a) Observation and understanding of the Universe.

Solution:The terms 'Event Horizon', 'Singularity', 'String Theory' and 'Standard Model' are sometimes seen in the news in the context of observation and understanding of the Universe.
In astrophysics, an Event Horizon This term is most famously associated with black holes. It's the boundary around a black hole beyond which nothing, not even light, can escape the gravitational pull. Understanding the event horizon is crucial to comprehending the extreme gravity and properties of these cosmic objects.
Singularities: are regions of space where the density of matter, or the curvature of spacetime, becomes infinite. In such locales, the standard concepts of space and time cease to have any meaning. Singularities are predicted to occur in all black holes and also in certain models of the Universe.
String theory: is a concept in theoretical physics that states the universe is constructed by tiny vibrating strings, smaller than the smallest subatomic particles. According to this theory, as the strings vibrate, twist and fold, they produce effects in many, tiny dimensions that humans interpret as everything from particle physics to large-scale phenomena like gravity.
The Standard Model of particle physics is the theory describing three of the four known fundamental forces (electromagnetic force, weak nuclear force, and the strong nuclear force — excluding gravity) in the universe and classifying all known elementary particles.

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

(a) a flight recorder in aeroplane
(b) a spot on the sun
(c) a place in Antarctica
(d) a collapsed star

Correct Answer: (d) a collapsed star

Solution:A 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.

8. 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 so strong that even light does not escape from it.
Code:

(a) Both (A) and (R) are true, and (R) is the correct explanation of (A).
(b) Both (A) and (R) are true, but (R) is not the correct explanation of (A).
(c) (A) is true, but (R) is false.
(d) (A) is false, but (R) is true.

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. For this reason, one can't see it by telescope.

9. Black Hole — [Uttarakhand P.C.S. (Pre) 2007]

(a) Does not emit any radiation.
(b) Converts UV radiation to infrared.
(c) Absorbs all radiations that fall on it.
(d) Is an imaginary concept.

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

Solution:A black hole absorbs all radiations that fall on it due to its high gravity.

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

(a) Away from the Sun
(b) Towards the Sun
(c) Towards North-East
(d) Towards South-East

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.

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