Scientists have recently found something entirely new -- a galaxy with the same mass as the Milky Way but with only 1 percent of our galaxy's star power. About 99.99 percent of this other galaxy is made up of dark matter, and scientists believe it may be one of many.
The galaxy Dragonfly 44, is said to be 300 million light years away. If scientists can track down a similar galaxy closer to home, however, they may be able to use it to make the first direct detection of dark matter.
Dark matter is the name given to a mysterious form of matter that we know must be there. Without something adding to the mass of the universe, things would tear apart. The laws of physics require some unknown, unseen kind of something to hold the universe together (while dark energy pushes it farther and farther apart). All we really know about dark matter is that it barely interacts with anything, including its own ilk.
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Scientists' investigations of the closest star, Proxima Centauri, has show that there is an Earth-sized planet orbiting about it. What is more, this rocky globe is moving in a zone that would make liquid water on its surface a possibility.
Proxima is 40 trillion km away but the discovery of a planet potentially favourable to life in our cosmic neighbourhood is likely to fire the imagination.
The distance between the star and its planet is considerably smaller than Earth's separation from the Sun (149 million km). But Proxima Centauri is what is termed a red dwarf star. It is much reduced in size and dimmer compared with our Sun, and so a planet can be nearer and still enjoy conditions that are potentially as benign as those on Earth.
Scientists have found that this planet is at 5% of the Earth's distance from the Sun. However, Proxima is 1,000 times fainter than the Sun. So the flux - the energy - reaching Proxima b is about 70% of what the Earth receives. It's like taking Earth a bit further away, but it's comparable.
Whether the temperatures on Proxima b are favourable for life to exist is going to depend on the presence of an atmosphere. An envelope of greenhouse gases would warm surface conditions and provide sufficient pressure to keep water - essential for biology - in a liquid state.
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