Category Astronomy

The Earth

What is the shape of the Earth?

The Earth is not a mere sphere but an oblate spheroid i.e., a sphere flattened slightly at the top and bottom (poles) and bulging at the central region. There is a little more flattening at the bottom than at the trop.

Why is the Earth an oblate spheroid rather than a sphere?

The Earth’s spinning motion causes the central region to bulge leading to flattened top and bottom.

Why is the study of the Earth significant for astronomers?

The Earth, the third planet from the Sun, is only planet that can be easily studied. A study of the Earth (as a planet) helps astronomers to understand the other planets better.

The Solar System

 

 

What are the “canals” of Mars?

In 1877 Italian astronomer G.V. Schiaparelli reported sighting a network of “Canali” (“Channels” in Latin) on Mars, but it was wrongly translated as “Canals” in English implying that the phenomenon is artificial. The canals of Mars are in fact only a natural phenomenon.

 

 

 

 

 

 

 

 

What are the “Rings” of Saturn?

Saturn possesses a large quantity of matter orbiting in t6he form of rings. They are classified into three major rings, A, B and C. Ring C is sometimes known by its nickname “Crepe Ring”. There is a large gap between rings A and B called the Cassini Division. The rings are made up of small blocks of matter too small to seen individually thereby creating an impression of a continuous sheet of material.

The Solar System

 

 

What is the true reason for the perturbations in the orbit of Mercury?

Mercury not only orbits the Sun but the orbit itself rotates.

 

 

 

 

Could the planets of the Solar System have formed differently?

It is matter of accident that the planets exist as they do. It has been postulated that the planets could have formed in a number of ways, all resulting in stable configurations.

Do the planets also twinkle?

Mercury and Venus twinkle when observed near horizon.

Is there any planet beyond Pluto?

Astronomers suspect the existence of a planet beyond Pluto (tentatively named Persephone but as yet undetected) roughly 5 times the Earth’s size, 100 a.u  distant from the Sun and orbiting the Sun once in more than 1000 years.

Among the objects of one of the voyages of the famous eighteenth century British explorer Captain Cook of the South Pacific, was an astronomical. Name it.

Observation of the transit of Venus.

 

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The Solar System

What are Sun Grazers and Earth Grazers?

These are small number of asteroids with highly elliptical orbits in relation to the Earth or the Sun, known as Earth Grazers and Sun Grazers, respectively.

 

 

 

 

 

 

 

 

 

 

 

How close to the Sun can a Sun Grazer Approach?

The notable example is the asteroid Icarus discovered in 1949 which is about 1.5 km in diameter and whose highly elliptical orbit takes it from an aphelion position beyond the orbit of Mars to a perihelion position within 28 million km of the Sun (less than half the mean distance of mercury from the Sun).

 

 

 

 

 

 

 

How close to the Earth Grazers approach?

Hermes, an asteroid less than 1 km in diameter, occasionally approaches the Earth within twice the Moon’s distance from Earth. Another asteroid Eros can approach the Earth within 23 million km.

 

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The Solar System

What are asteroids and where are they?

Asteroids are small bodies orbiting the Sun. Almost all of them (99.8%) move in orbits between those of Mars and Jupiter, in a zone known as the Asteroid Belt.

How many asteroids exist and how many been studied so far?

About 100,000 and 2,000 respectively.

How were asteroids created?

Asteroids are supposed to represent space debris scattered by the perturbing effects of Jupiter’s gravity.

What is the estimated total mass of the asteroids?

The estimated total mass of all the asteroids is less than 0.1 per cent of the Earth’s mass.

What is the size range of the asteroids?

Asteroids generally range in diameter from less than a kilometer to about 800 km.

The Solar System

What are the “Morning Star” and the “Evening Star”?

Mercury and Venus, due to their inferior orbits, always appear close to the Sun and are difficult to see except in the Twilight hours. Mercury and Venus are sometimes referred to as “Morning Star” and “Evening Star”. However, they are really not stars but planets.

 

 

 

 

 

 

 

Why did the ancients mistake the planets Mercury and Venus for stars?

Mercury and Venus appear bright during twilight hours when the stars are usually faint. Mercury is sometimes as bright as the bright-stars Sirius. Venus appears brighter than Mercury <sometimes even ten times brighter>.

 

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