• Summer Solstice: On June 21 every year, the summer solstice occurs in the Northern Hemisphere, which means that the North Pole is tilted towards the Sun.
• This results in the Tropic of Cancer (Statement 2) and Arctic Circle (Statement 4) experiencing sunlight for more than 12 hours.
• The Tropic of Capricorn (Statement 3) is in the Southern Hemisphere and does not experience more than 12 hours of sunlight on June 21. 
• Equator (Statement 1): The Equator always receives roughly 12 hours of sunlight throughout the year, so it does not experience more than 12 hours of sunlight specifically on June 21.
• Therefore, the correct answer is option (d): 2 and 4.

Figure: Revolution of the Earth and Seasons

•   Statement I is incorrect: Contrary to dwarf stars, giant stars have shorter lifespans because their larger cores consume nuclear fuel at a much faster rate, leading to a quicker depletion of energy.

•   Statement II is correct: Giant stars, having greater mass, possess hotter and denser cores, which drive more vigorous nuclear reactions, resulting in higher brightness and energy output.

•   Description of Cepheids and Nebulae is reversed.

https://www.thehindu.com/sci-tech/science/best-from-science-journals-alien-radioactive-element/article60682900.ece

(19 May 2021)

https://www.thehindu.com/children/the-letter-that-changed-the-universe/article66492665.ece(19 February, 2023)

https://www.thehindu.com/sci-tech/science/webb-peers-into-the-depths-of-tarantula-nebula/article65870531.ece(09 September, 2022)

https://www.thehindu.com/children/the-fascinating-discovery-of-an-optical-pulsar/article38166637.ece(15 January 2022)

•   An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere.

•   Of the roughly one million known asteroids the greatest number are located between the orbits of Mars and Jupiter, approximately 2 to 4 AU from the Sun, in the main asteroid belt.

•   India is a large country spanning over 30° of longitude. It is unusual in having a single time zone all over the country, 5½ hours fast. If the direction of rotation of earth is reversed then Indian Standard Time will be – 5½ hr. When it is noon the time is 12:00; that will be 6:30 A.M.in place of 17:30 P.M. or 5:30 P.M.

From the given figure

•   '1'indicates Calcutta port which is a tidal port, situated at river Hoogly.

•   '2'indicates Paradeep port of Orissa.

•   '3'indicates Kochi of Kerala

•   '4'indicates Kandla port of Gujarat is tidal port. Paradeep, Kochi and Kandla are natural ports on the sea coast.

•   When it is noon along 82° 30' longitude, along 0° E or W degree of longitude it will be 6.30 a.m. The Earth has been divided into 24 time zones of one hour each. Each of these zones covers 15 degrees of longitude.

•   This airplane taking off from N30 E50 would have to be a seaplane or floatplane. That location is in the Persian Gulf off the coast of Iran. 

•   The opposite side on the globe would be S30 (the other side of the equator) and W130 or south of the Pitcairn Islands in the South Pacific.

•   Mars is the planet that is very similar to Earth and many studies are going on to study the planet. A Martian day is 1 day 37 mins long and its rotation axis is tilted the same way as of Earth.

•   Uranus's day length is 17 hrs

•   Neptune's day length is 16 hrs

•   Saturn's day length is 10 hrs.

•   Seasons are caused by Earth's changing position as it revolves around the Sun. Earth is closer to the Sun in December and January and farther away from the Sun in July and August.

•   Accra uses UTC+0 while Dublin, Madrid and Lisbon use UTC+01:00.

•   Greenwich Mean Time is the mean solar time at the Royal Observatory in Greenwich, London, reckoned from midnight. At different times in the past, it has been calculated in different ways, including being calculated from noon; as a consequence, it cannot be used to specify a precise time unless a context is given.

•   The Pole Star is aligned with the Earth's axis of rotation. So, when we observe in its direction, we're looking in the direction of north. In addition, just like the Sun, stars rise in the east and set in the west.

•   Pole star's position with respect to rotating earth never changes and it always points to the north direction. Thus, if the person keeps the pole star to his left, he can be sure of walking in the eastern direction in which his village is located.

•   Jupiter revolves or orbits around the Sun once every 11.86 Earth years, or once every 4,330.6 Earth days.

•   At 90° angular separation from the Sun seen from the Earth’s surface will be half of the Moon's illuminated side and half of its night side. This phase is called a quarter phase because you can see a quarter of the Moon's entire surface (and 90 degrees is one-quarter of 360 degrees).

•   The earth's spin axis is tilted with respect to its orbital plane. This is what causes the seasons. When the earth's axis points towards the sun, it is summer for that hemisphere. When the earth's axis points away, winter is expected.

•   The earth travels about 107,000 kilometers per hour. This means that our planet moves around the sun at an average speed of 30 km per second. Earth’s speed is not constant as the earth has an elliptical orbit. When the Earth is the closest to the sun (Perihelion), it moves the fastest.

•   Note: It’s a repeated question.

•   Titan is the satellite of Saturn.

•   Halley's orbital period has varied between 74–79 years since 240 BC. Its orbit around the Sun is highly elliptical. The perihelion, the point in the comet's orbit when it is nearest the Sun, is just 0.6 AU.

•   If it is given that the difference between times of two places is 2 hours and 20 minutes then, the difference in their longitudes would be 35°. The time contrast between every longitude is 4 minutes. 2 hours and 20 mins is 140 mins so,

•   140/4 =35 degrees

•   Delhi is slightly away from equator, so sun is slightly tilted from being over head. Mumbai and Chennai are south of the tropic of cancer, while Delhi is north of it. Due to the tilt of axis of rotation of the earth, parts of the earth north of the tropic of cancer will never have the noon sun exactly overhead.

•   Delhi is located North of Tropic of Cancer so the Sun is never overhead at Delhi.

•   The Moon orbits Earth once every 27.3 days and spins on its axis once every 27.3 days. This means that although the Moon is rotating, it always keeps one face toward us. Known as “synchronous rotation,” this is why we only ever see the Moon's nearside from Earth.

•   There are eleven time zones in Russia. The reason for many time zones is to have long east-west stretches. Each time zone is named after the largest city within the zone. Prior to 1990, all time zones of the USSR were one hour ahead from today.

•   With its 11 local times, Russia is one of the countries with the most time zones worldwide. While France and its dependencies stretch across 12 time zones, Russia holds another world record: 10 of the country's 11 time zones cover a contiguous landmass—only the Russian exclave of Kaliningrad, wedged between Lithuania and Poland, breaks that pattern.

•   Revolution along with the earth’s tilted axis leads to changing seasons across the hemispheres.

•   The reason the Earth has seasons is because the Earth is tilted 23 1/2oon its axis.

•   During the Northern Hemisphere Summer, the North Pole points toward the Sun and in the Northern Hemisphere Winter, the North Pole is tilted away from the Sun.

•   Difference in Local Times between Places P and Q

o  Place P has a longitude of 45° E

o  Place Q has a longitude of 60° W

•   Calculation of Time Difference:

o  For every 15° of longitude difference, there is a time difference of 1 hour

o  The total longitude difference between P and Q is 105° (45° + 60°)

o  Therefore, the time difference between P and Q is 7 hours

•   Therefore, the correct answer is:(a) 7 hours

•   Both the rotation of earth around its own axis and the revolution of the earth around the sun causes difference in the climates of Northern and Southern Hemisphere. Also, the distribution of landmass and oceans also affects the climate of northern and southern hemisphere. Northern Hemisphere has much area covered by landmass and southern hemisphere has more are covered by oceans.

•   The weight of an object depends on the force of attraction with which it is attracted towards the centre of the Earth.

•   At the pole, this force is greater as on account it has less distance from the centre of the Earth. This is the reason why the body weighs more at the poles than at the equator.

•   Since, the force of attraction is higher on the object at poles than at the equator as the distance of the pole is less to the distance of the equator from the center of the earth.

There are two main reasons for that:

1.  Earth is not perfectly spherical in shape. As, it has less radius on poles in comparison to equator where it is more.

2.  Earth is spinning with more angular velocity. With more angular velocity, at equator the Earth spins decrease as we move towards the poles.

Thus, the weight of an object is greater at pole than the weight of object at the equator.