My Science School

Trojan asteroids are asteroids that share an orbit with a planet and are located at the leading (L4) and trailing (L5) Lagrangian points of the planet’s orbit. Lagrangian points or Lagrange points are locations in space where the combined gravitational forces of two large bodies, such as the Earth and Sun, equals the centripetal force required for a small object to move with them. Thus, if a spacecraft is to be parked at this point, the fuel consumption required to keep it in place can be reduced. There are five Lagrangian points in total, of which three are unstable (L1, L2, L3) and two are stable (L4 and L5). L4 leads the orbit of the planet and L5 follows.

How were they discovered?

On February 22, 1906, German astrophotographer Max Wolf discovered an asteroid with an unusual orbit. This asteroid remained ahead of Jupiter as the planet moved. To him, it seemed as though the asteroid was trapped in Jupiter’s orbit around the Sun. Meanwhile, German astronomer Adolf Berberich observed that the asteroid was nearly 60 degrees in front of Jupiter. This reminded Swedish astronomer Carl Charlier of a behaviour predicted nearly a century earlier by Italian-French mathematician Joseph-Louis Lagrange. Lagrange had stated that if a small space body such as an asteroid were to be placed at one of two stable points in a planet’s orbit around the Sun, the asteroid would remain stationary from the planet’s perspective.

This is when Charlier realised that the asteroid discovered by Wolf was caught in Jupiter’s L4 Lagrange point. Until this discovery, Lagrange’s prediction was only a mathematical exercise, but now there was photographic proof that Lagrange was right.

How did they get their name?

About eight months after Wolf’s discovery, one of his students, August Kopff discovered an asteroid in Jupiter’s L5. And then again a few months later, he discovered another asteroid caught in Jupiter’s L4. Once these discoveries were made, astronomers started wondering what to call these asteroids. While most asteroids at this point in time were named after women from Roman and Greek mythology, Austrian astronomer Johann Palisa suggested the names Achilles, Patroclus, and Hektor after characters from The Iliad (a Greek poem set during the Trojan War), due to the strange orbit of these asteroids.

 

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Stars all look the same colour, don’t they? That’s true if you see them with the naked eye. Through a telescope the picture changes. Once you look at stars when they are magnified, you see that they all have different colours.

Surface temperature controls the colour of a star. Our most familiar one is the sun. That has a surface temperature of around 5000  and is yellow-white in colour. There are plenty of stars in the universe far hotter than the sun. The hottest are twice as hot on the surface, and these are blue. Surprisingly, red stars are the coolest ones. The surface temperature on these is about 3000 . Knowing this, scientists are able to estimate the surface temperature of stars by carefully measuring their colours.

 

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Today there are many artificial satellites that revolve round the Earth. Why is all the time, money and effort required to launch them considered worthwhile? The answer is that the satellite performs many useful scientific tasks as it journeys through space.

Artificial satellites can act as spies that seek out military installations and equipment on the Earth below. Another function is communications between distant points of the globe.

They can study the solar radiation and environment of space and this knowledge helps us to understand the forces at work on our own planet and the causes of natural phenomena which effect our living conditions.

Meteorological satellites also exist which record details of weather conditions throughout the world and help in weather forecasting.

 

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During the 1700s after a great deal of hard work astronomers were able to calculate the speed and direction of many stars. By 1805 the astronomer Herschel proved that the Sun itself was subject to the same laws of movement. We now know that the Sun with its whole accompaniment of planets travels through space at the terrifying speed of about 270 kilometres a second together with the whole galaxy in which the solar system lies. The Sun also travels along a path of its own which is directed at a point in the heavens near the star Vega.

Herschel had studied the distant nebulae which astronomers before him believed to be millions of stars. Even the Milky Way was a nebula, but it was much brighter than the others and therefore must be nearer.

Herschel then thought that the Sun, like hundreds of other stars visible from the Earth, was part of huge nebula, separate from all the others and forming a universe of its own:  the galaxy.

During the 1870s the first powerful telescopes found other nebulae outside the galaxy and this proved that Herschel was right. New searches were made in our own century with the installation of the Mount Wilson telescopes in 1905 and the one at Mount Palomar in 1948.Today we can even begin to draw a map of the galaxy. It appears to be shaped like a 100,000 light years (one light year is equal to 10 million kilometres) and contains about 100,000 million stars.

 

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One of the weirdest features in space travel is the spacesuit worn by astronauts, with its huge spherical helmet, the tunic, the bulky gloves and boots and all the various gadgets and fittings.

The space-suit is a highly perfected machine in itself. It consists of no fewer than fifteen layers of special materials to protect the body of the astronaut. The space suit must provide oxygen for the astronaut to breathe and protect the astronaut from the vacuum and heat or cold of space. It must also be flexible enough to allow the astronaut to move freely. For travel in space, the astronaut wears an MMU (manned maneuvering unit), which contains small gas-powered thrusters. 

The space-suit must also contain food and water supplies, fitting to dispose of bodily wastes and surface to deflect heat and radiation. The helmet visor requires protective tilters to prevent the astronaut from viewing the Sun directly and risking severe dazzling and retinal burns. The suit also has to be fireproofed to the maximum possible extent.

The space-suit took years and millions of dollars to develop.

 

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Mercury - Swift Planet

Because it moves quickly around the Sun and circles it faster than all the other planets.

Venus - Morning and Evening Star

The two nicknames given to Venus are because it rises and sets each day, like the Sun. It is visible from Earth, like a star in the sky, in the morning before the Sun rises, and in the evening as soon as the Sun sets.

 

Earth - Blue Planet

Most of the Earth is filled with water, and this makes the planet appear blue from space.

Mars - Red Planet

Mars is nicknamed so because it appears in the sky as an orange-red star. Toray, scientists know that Mars appears so due to the net on the Martian rocks.

Jupiter - Giant Planet / Gas Giant

Jupiter is the largest planet in the solar system. In fact, it is so big that all the other planets in the solar system could fit inside it! It is also known as the Gas Giant because its atmosphere is mostly made up of hydrogen and helium gas just like the Sun.

Saturn - Ringed Planet

Saturn is known so because of its rings. The other gas giants in the solar system, such as Jupiter, Uranus and Neptune also have rings, but only Saturn’s are visible prominently.

Uranus - Sideways Planet / Bulls Eye Planet / Ice Giant

Uranus is four times the size of the Earth ant is the coldest planet in the solar system. Hence, it is called the le Giant. It is known as the Sideways Planet because it rotates on its side. And, as for the nickname Bulls-Eye Planet, it is because Uranus’ rings are vertical, unlike Saturn's which are horizontal. This makes it appear like a bulls-eye on a target.

Neptune - Big Blue Planet / Windy Planet

Neptune looks blue from space, just like Earth, but i many times larger than our planet. Hence it is called the Big Blue Planet. It is sometimes also called the Windy Planet because winds in Neptune can whip clouds of frozen methane at speeds of more than 2.000 km/h!

 

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For many years, scientists believed that Jupiter's moon lo was geologically dead. This means it didn't have things such as earthquakes, newly forming mountains or volcanoes. However, it turns out the scientists were wrong about lo. In 1979, when NASA's Voyager 1 spacecraft took close up pictures of lo, the pictures showed a massive plume erupting from lo's surface into space. That's when they realise that lo did not just have volcanoes, it had active volcanoes. And, lo was no longer considered geologically dead. When these pictures were taken it was the first time an erupting volcano was found anywhere other than Earth. So that leaves us wondering, do all the planets and their moons have active volcanoes? Let's take a look

Mercury: The planet once had active volcanoes, but not anymore. Scientists believe violent volcanic eruptions that shaped Mercury's surface, likely ended about 3.5 billion years ago.

Venus: Venus, on the other hand is covered with volcanoes. The hottest planet in our solar system has over 1,000 volcanoes, including some that might still be active, according to what scientists think.

Mars: Mars is home to Olympus Mons, the solar largest volcano in our system. It is also the mountain in our solar largest led our solar system Mars is filled with tall volcanic mountains, and while scientists haven't seen an eruption on Mars, they think there could be some in the future.

Jupiter: Scientists have found volcanoes and observed volcanic activity only on lo, Jupiter’s moon. Eruptions from lo's volcanoes are so massive that it can been seen by a spacecraft that is pretty far from lo.

Saturn: Saturn's moon Enceladus has cryovolcanoes. These volcanoes are similar to regular volcanoes, except they spew water and other gases like geysers.

Uranus: Since it is a gas planet, it does not have any volcanoes.

Neptune: While Neptune doesn't have volcanoes as it is a gas planet, its frozen moon, Triton, has cryovolcanoes that are active.

 

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