Category Kids Queries

Hominids evolved and developed for millions of years prior to the arrival of Homo sapiens on the Earth. This evolution was slow. The development of a new skill or tool often took thousands of years. With the arrival of Homo sapiens, this all changed. The speed of advancements increased dramatically. Instead of thousands of years, great progress was made in hundreds or even dozens of years.

The first Homo sapiens are believed to have been the Neanderthals. Neanderthal people first appeared on the Earth around 200,000 years ago in Africa. They migrated from Africa to the rest of the world around 100,000 years ago. Neanderthals were around five to six feet in height. They had thick sturdy bones, and muscular shoulders, legs, arms and necks. Neanderthals also had large brains. In fact, their brains were slightly larger than those of modern humans.

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The Moon is about 4.5 billion years old and is the only natural satellite in our Solar System.

The moon formed about 30–50 million years after the Earth formed.

The moon came about when a large object hit the Earth and blasted out rocks that all came together and orbited round the Earth.

Eventually they all melted together like in a big heated pot, cooled down and became the Moon.

For another 500 million years pieces of rock kept striking against the surface of the Moon.

You can see the surface of the Moon by using a pair of binoculars or a small telescope. The Moon’s surface shows the damage caused by these large pieces of rock hitting it billions of years ago.

The surface is covered in craters, pits and scars.

The first man to make proper maps of the moon was Galileo.  He didn’t invent the telescope but by 1609 he had developed a telescope that could magnify objects up to 20 times.

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Measurements made in the 18th century to determine how old the Earth is were based on the rate of the Earth’s cooling. The results of these computations vastly underestimated the age of the Earth to be in the hundreds of thousands of years.

The ability to accurately date our planet — which formed out of debris left behind by the birth of the sun — developed with the understanding of radioactive decay. Radioactive substances release subatomic particles at a very steady rate. Sometimes the age of an object can be determined by comparing present amounts of a radioactive substance with the supposed original amount in the object. Uranium is a particularly well-understood, naturally radioactive element.

By measuring lead to uranium ratios in ancient rock samples, in 1953 scientists deftly put Earth’s age at 4.5 to 4.6 billion years, an estimate that stands today.

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The sun is around 4.6 billion years old. Our 4.6-billion-year-old sun will become a red giant in about 5 billion years after it burns up all the hydrogen at its core. By that time, it will have extended in size and swallowed up Venus and Mars, and Earth will be long gone.

In fact, the scientists note that Earth will be gone in about a billion years. That’s because every billion years or so, the sun becomes 10 percent brighter as it ages. The increased brightness will be enough to evaporate our oceans, making life on our planet impossible.

After becoming a red giant, the sun will its dying days turn into a planetary nebula, a massive ring of luminous, interstellar gas and dust left behind.

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One of the basic ways to look at the age of the Milky Way is to look at globular clusters. These are dense clusters of stars that are distributed in a kind of halo around our galaxy. We know that the stars within a globular cluster form around the same time, and we can determine their age by looking at things such as the percentage of their stars that are red dwarfs, or the temperatures of their white dwarfs.

The red dwarf measure is useful because red dwarfs can last for trillions of years, unlike larger stars which only last a few billion. So if a group of stars form at the same time, the larger stars will die off sooner, while the red dwarfs continue to shine. So the more red dwarfs a globular cluster has, the older it is. The white dwarf method relies on the fact a white dwarf is the remnant of a Sun-like star. Once a white dwarf forms, it has no way to produce new energy, so it gradually cools. The cooler the white dwarfs in a globular cluster, the older it is.

It turns out that the oldest of the globular clusters surrounding our galaxy are about 13 billion years old, which means the Milky Way must be at least that old. 

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According to research, the universe is approximately 13.7 billion years old. Hubble has helped to measure the age of the universe using two different methods. The first method involves measuring the speeds and distances of galaxies. Because all of the galaxies in the universe are generally moving apart, we infer that they must all have been much closer together sometime in the past. Knowing the current speeds and distances to galaxies, coupled with the rate at which the universe is accelerating, allows us to calculate how long it took for them to reach their current locations. The answer is about 14 billion years. The second method involves measuring the ages of the oldest star clusters. Globular star clusters orbiting our Milky Way are the oldest objects we have found and a detailed analysis of the stars they contain tells us that they formed about 13 billion years ago. The good agreement between these two very different methods is an encouraging sign that we are honing in on the universe’s true age.

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