Category Physics

WHERE IS THE ANTARCTIC CIRCLE?

The Antarctic Circle is a parallel of latitude on the Earth at approximately 66.5 degrees south of the equator. On the day of the southern summer solstice (around December 22 each year), an observer on the Antarctic Circle will see the Sun above the horizon for a full 24 hours.

Observers further south than the Antarctic Circle will see the Sun remain above the horizon for many days, and at the South Pole, there is a six-month ‘day’ that starts on the autumnal equinox changing to a six-month ‘night’ on the vernal equinox.

The 66.5 degree angle comes from the tilt of the Earth’s rotation axis (23.5°), such that 90° – 23.5° = 66.

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WHERE IS THE ARCTIC CIRCLE?

The Arctic Circle is a line of latitude that circles the Earth at approximately 66° 33′ 47.2″ north of the Equator. How was that strange number determined? The position of the Arctic Circle is at the latitude above which the sun does not set on the summer solstice and does not rise on the winter solstice.

This is what causes the Arctic to have a very long continuous night each year and a very long continuous day. The length of these long continuous days and nights are six months each at the North Pole. Their length decreases with distance from the North Pole.

The latitude of the Arctic Circle is slowly drifting northward at a speed of about 15 meters per year. On July 2, 2018 it was at approximately 66° 33′ 47.2″ north of the Equator. This drift has nothing to do with climate change. Instead, the drift occurs because the Earth wobbles on its axis of rotation in a 40,000 year cycle in response to the gravitational attraction of the moon.

To most of the general public, using the Arctic Circle as the defining southern boundary for “the Arctic” is easy and makes total sense. However, some researchers believe that there are better ways to draw a map of the Arctic.

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WHAT IS THE EQUATOR?

The equator is the circle that goes round the centre of Earth. It is perpendicular to the axis and divides the planet into two equal hemispheres (or half-spheres), the Northern and the Southern.

The Earth’s Equator is the imaginary line that runs around the centre of the globe at 0 degrees latitude, at equal distance between the North and South Poles. Like the other lines of latitude, it’s based on the Earth’s axis of rotation and its orbit around the sun. It is the longest of Earth’s five circles of latitude, the others being the polar circles, and tropical circles. This is because of how the Earth bulges around its centre.

The Equator is just under 25,000 miles long, wrapping around the entire Earth. The Equator divides the Earth into northern and southern hemispheres, with both experiencing different amounts of daylight at different times. This, weather, climate and the seasons we experience are a result of the Earth’s tilt on its axis and its orbit around the sun. The northern and southern hemispheres are either turned toward or away from the sun depending on the Earth’s position whilst it’s orbiting the sun.

When the Sun is directly above the Earth’s Equator, sunlight shines perpendicular to the Earth’s axis, and all latitudes have a 12-hour day and 12-hour night. The Sun passes directly over the equator twice a year, on the March and September equinoxes.

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WHY ARE LATITUDE AND LONGITUDE IMPORTANT?

Two points on Earth can lie at the same latitude but still be far away from each other. Similarly, two distant points may lie on the same longitude. But only one point lies on a particular combination of latitude and longitude. So latitudes and longitudes are necessary for locating an exact point on Earth.

The importance of longitude and latitude are:

  • Latitudes help in identifying and locating major heat zones of the earth.
  • Latitude measures the distance between the north to south from the equator.
  • Latitude helps in understanding the pattern of wind circulation on the global surface.
  • Longitude measures the distance between the west to earth from the prime meridian.
  • Both longitude and latitude help us measure both the location and time using a single standard.
  • The lines of longitude and latitude help us in measuring the distance from the Earth’s Equator
  • Latitudes help us to find out the distance of any place from the Equator, which is base on its degree of latitude.
  • Longitude and latitude help us to find the location of any place on earth. These coordinates are what the Global Position System or GPS

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What is nebula?

A nebula is a formation in space which is constituted mostly of helium, dust, and other gases in various concentrations. The shape and size of a nebula varies, and as such there can be various types of formations having different sizes. Very often, they are huge in size, and their diameters can be a number of light years across. It is derived from Latin, and as such means a cloud. Nebulae exist in the space between the stars—also known as interstellar space. The closest known nebula to Earth is called the Helix Nebula. It is the remnant of a dying star—possibly one like the Sun. It is approximately 700 light-years away from Earth.

It is not clear how exactly a nebula is formed, but it is believed that they are formed by the collapsing of interstellar medium, which then come together because of the gravitational pull of the particles. Nebula is an important object for observation by researchers, who derive significant information about the formation process of stars and planets. A nebula is capable of exerting a gravitational pull, and the force is derived from the particles which come together to form the nebula. With more particles coming together, not only does the nebula increase in proportion, but its gravitational pull also gathers more power and intensity. A nebula is also believed to be one of the primary stages in the formation of stars. Scientists are of the opinion that a nebula can be used to create a trajectory of stellar evolution. There are various nebulae that are in existence at present, though numerous others may exist in the far-flung corners of space that remain to be observed. Some of the most popular ones are Pelican, Crab, Eagle, and Ring Nebula, with Ring being among the most observed ones on the planet.

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WHAT MAKES THE SEASONS?

Earth is always tilted the same direction as it orbits the Sun. So when Earth is on one side of the Sun, the northern hemisphere is tilted closer towards the Sun, making it warmer. At the same time, the southern hemisphere is tilted away from the Sun, and is, therefore, colder. When Earth reaches the other side of the Sun, it is the opposite, so it’s winter in the northern hemisphere and summer in the southern.

Seasons happen at different times in different parts of the world. The tilt of the Earth doesn’t change as it rotates around the Sun. But the part of the planet that gets the most direct sunlight does change.

The Northern Hemisphere is tilted away from the Sun from September to March. That means the northern half of the planet doesn’t get as much light and heat from the Sun. This causes autumn and winter. During the same months, the Southern Hemisphere is tilted towards the Sun. That means the southern half of the planet gets spring and summer.

From March to September, the Northern Hemisphere is tilted towards the Sun. So that’s when the northern half of the Earth experiences spring and summer. During the same months, the Southern Hemisphere experiences autumn and winter.
Other planets also have seasons. But the length and intensity of each season varies from planet to planet.

  • On Earth, seasons last between 90 and 93 days.
  • On Venus, seasons last between 55 and 58 days.
  • On Mars, seasons change about once every six months. Summer lasts 199 days and winter lasts 146 days.
  • On Saturn, seasons last about seven years.
  • And if you lived on Neptune, you would have to wait more than 40 years for the seasons to change!

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