Earth is 'pretty normal' within the universe and there could be many more planets like ours, study finds

An Earth-like planet is 'just waiting to be found' say researchers

Artists impression of white dwarf star (on right) showing dust disc, and surrounding planetary bodies (Nasa)

The Earth is “pretty normal” as far as the universe goes and there could be many more planets like our own than we ever realised, according to a new study.

The building blocks that helped create our own planet are spread across the universe, the researchers discovered. As such, other planets like our own are probably out there “just waiting to be found”, according to researchers.

The study is one of the biggest investigations into how other planetary systems are formed and what materials are used, as well as looking at what that might mean for other Earth-like planets elsewhere in the galaxy.

Looking for such planets and trying to understand their makeup is difficult because any signals from them are usually completely drowned out by the stars that are near them, the researchers said. So they looked into other ways of examining those planets and examining their composition.

“Most of the building blocks we have looked at in other planetary systems have a composition broadly similar to that of the Earth,” said researcher Dr Siyi Xu of the Gemini Observatory in Hawaii.

The discovery was made by looking at white dwarfs, stars that have shrunk down to be very small and dense, a fate that awaits our own star in just 5 billion years.

As they get so small, they pull in other material from nearby. That can then be seen as it moves closer to the star, allowing scientists to explore what the planets that surround it are made of.

“White dwarfs’ atmospheres are composed of either hydrogen or helium, which give out a pretty clear and clean spectroscopic signal,” said Dr Xu. ”However, as the star cools, it begins to pull in material from the planets, asteroids, comets and so on which had been orbiting it, with some forming a dust disk, a little like the rings of Saturn.

“As this material approaches the star, it changes how we see the star. This change is measurable because it influences the star’s spectroscopic signal, and allows us to identify the type and even the quantity of material surrounding the white dwarf. These measurements can be extremely sensitive, allowing bodies as small as an asteroid to be detected”.

Looking through those measurements, scientists found that most of the planets were made up of the same materials that are beneath our feet.

“This would mean that the chemical elements, the building blocks of earth are common in other planetary systems,” said Dr Xu. ”From what we can see, in terms of the presence and proportion of these elements, we’re normal, pretty normal. And that means that we can probably expect to find Earth-like planets elsewhere in our galaxy”.