My Science School

 

What are the Solstices?

During the year, the position of the Sun in the sky, as viewed from the Earth shifts from north to south and back again. In other words solstice occurs on either to the days on which the Sun is farthest north or south of the celestial equator each year. The points of solstice correspond to the northernmost and southernmost positions of the Sun in the sky.

 

 

 

What is the structure of the Earth?

Earth has a molten liquid core of iron, nickel and magnesium silicates. At the surface of the Earth is a solid layer called the crust. A semi fluid zone called the mantle exists between the crust and core. About 70% of the Earth’s surface includes north and south polar icecaps it is covered with water.

 

 

 

 

 

 

 

 

What is the precession of the Earth’s axis?

The Earth’s axis does not remain steady but wobbles like that of a tilted spinning top. This wobbling is called the precession of the Earth’s axis.

 

What causes the change in seasons on Earth?

In the northern hemisphere, the Earth’s 23.50 tilt towards and away from the Sun during June and January causes’ summer and winter respectively. It would be the converse in the converse in the southern hemisphere.

Does the change in the Earth-Sun distance during an year have any appreciable effect upon the seasons on Earth?

No.

 

 

Do the hemispheres have identical temperatures during summer and winter?

Theoretically, the Earth should have a slightly hotter climate in the southern hemisphere compared to the northern hemisphere. However, the larger mass of ocean in the southern since the ocean heats up and to even down more slowly than land areas.

 

 

 

Continue reading "The Earth"

Port Blair                           -41          

Guwahti                          -37

Patna                             -11

Lucknow                        +6

Delhi                             +21

Srinagar                       +31   

Panaji                           +35        

 

Port Blair                           -41          

Guwahti                          -37

Patna                             -11

Lucknow                        +6

Delhi                             +21

Srinagar                       +31   

Panaji                           +35        

 

 

 

 

What is a civil day?

A civil day is the day of 24 hours used routinely on Earth for setting clocks i.e., 24 hours divided into two portions- day time and night time- depending on whether the Sun Shines in the sky or not.

 

 

 

 

 

 

Does the difference between the civil and astronomical days have any significance in astronomical observations?

 

 

Since the civil day is 3 minutes and 56 seconds longer than the astronomical day, any star in the sky will rise 3 minutes and 56 seconds earlier every day compared to the previous day.

 

What is the time difference between a lunar and a solar year?

A solar year has 365 days. A lunar year has 354 days, and is based on twelve complete moon phase cycles or lunation.

Are all calendars based on the solar year?

No. Some calendars (such as those of the Mohammed am era) are based on the lunar year.

 

 

 

What is an astronomical year?

An astronomical year (also known as sidereal year) for a planet is the time taken by the planet to make a complete revolution around the Sun. In the case of the Earth, the sidereal year is equal to 365.2564 mean solar days or 365 days 6 hours 9 minutes and 9.5 seconds.

 

 

 

 

What are the regions or zones of the Earth?

The regions north of the Arctic Circle and south of the Antarctic Circle are called the Polar Regions or frigid zones.

The region between the Tropic of Cancer and the Tropic of Capricorn is called the Torrid Zone. The regions between the Tropic of Cancer and the Arctic Circle and between the Tropic Capricorn and the Antarctic Circle are called the north and south temperate zones respectively.

 

 

 

 

 

 

What are the polar ice caps?

Extremely cold temperatures of the Polar Regions cause ice formation on land and sea, resulting in a permanent blanket of ice around the poles called the polar ice caps.

 

Continue reading "The Earth"

 

Can all spherical celestial bodies be imagined to have their own equator, poles, latitudes and longitudes?

Yes, all spherical celestial bodies are imagined to have their own equator, poles, latitudes and longitudes.

 

 

 

What are the tropics?

The latitude 23.50 North of the Earth’s equator is called the tropic of cancer.

The tropic of Capricorn is the latitude 23.50 south of the Earth’s equator. There are limits of the area of earth’s surface in which the Sun can be directly overhead.

The peak activity was, however, visible only in the north Pacific region.

 

Continue reading "The Earth"

 

 

What are latitudes?

Latitudes are imaginary lines between the equator and the poles which run parallel to the equator and divide the surface of the Earth into parallel segments. Latitudes are also called “Parallels” or “Parallels of Latitude” e.g. 20 degrees latitude.

 

 

 

 

What are longitudes?

Longitudes are imaginary-lines through the geographic poles which run circumferentially and intersect the surface of the Earth dividing it into segments e.g.  20 degree w longitudes. (For example, if the Earth is imagined as an orange, the longitudes would divide it into its natural “slices”). Longitudes are also called “Meridians” or “Meridians of longitude”. The  zero degree meridians is also called the “Greenwich” meridian since it passes through the town of Greenwich in England.

 

 

 

What is the speed of rotation of the Earth?

The Earth spins faster during September than during March in any year.

 

 

 

 

 

 

 

What are poles?

All the bodies which rotate on their axes, such as the Earth, Sun, Moon, planets, etc. are said to have two poles, called North Pole and South Pole for connivance. They are the points at which the axis of rotation intersects the surface of the body. Hence, the Earth has a north pole and a south pole, and the line passing through the centre connecting the poles is the axis of rotation of the Earth.

 

How are the poles identified with respect to surface features on the Earth?

The poles are imaginary points and are never identified by any natural features on the Earth’s surface.

Continue reading "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.