Professor Brian Cox has been back on our screens this month in his latest BBC2 series Wonders of the Universe. Over the past few weeks, the Prof has guided us through the Universe as we’ve never seen it before! Our Universe is estimated to be around 13.7 billion years old, 93 billion light years wide and contains over 100 billion galaxies, each containing hundreds of billions of stars. Those numbers do start to hurt your head when you think about it, so instead Sinead McNicholl decided to list her personal seven wonders of our great Universe.
Stars are balls of gas held together by gravity and are comprised of hydrogen and helium gas. The colour of stars is determined by their temperature, the hottest stars are blue-white whilst the coolest stars are red, you can even pick out the hotter and cooler stars in the night sky with the naked eye! Stars are responsible for most of the naturally occurring elements and this is why I have named them on my list of wonders of the Universe. Without stars we would not exist! The calcium in our bones and the iron in our blood came from inside stars that died long before the Solar System ever formed. The most important star for us is The Sun which has a surface temperature of 5,500 Degrees Celsius and of course is the closest star to the Earth. The Sun gives us the right amount of heat and light for life to exist.
6- Black Holes
Black holes are usually a favourite of Science Fiction movies and novels because they are intriguing. Hollywood can portray them as time-travel tunnels or portals to other dimensions! Are they really? Well, we actually know very little about them as it is impossible to see a black hole directly because no light can escape from them, hence why they are called ‘black’ holes. But we do know that they are the end point of huge stars. They use the power of gravity to pull things towards them and are made up of three main parts. The outer layer of a black hole is called the Outer Event Horizon. Within the Outer Event Horizon you would still be able to escape from a black hole’s gravity because gravity is not as strong here. The middle layer is called the Inner Event Horizon. If you didn’t escape the black hole’s gravity before now, then you have missed your chance to get away as the gravity in this layer is much stronger and will not let go of objects it captures. At this point you would begin to fall towards the centre of the black hole which is called the Singularity , a point in space beyond the understanding of present day science, and this is where the black hole’s gravity is the strongest. What happens there, no one knows.
5- Hypervelocity Stars
Linked to black holes we have hypervelocity stars, also called exiled stars, which were first proposed to exist in 1988. Like the name suggests they are stars which are travelling at high speed from a galaxy after interaction with a black hole. These stars are moving very fast, to show you how fast, just think that ordinary stars in the galaxy have velocities around 100 km/s, while hypervelocity stars have velocities of up to 1000 km/s! It was in 2005 that the first hypervelocity star was discovered by astronomers using the Multiple Mirror Telescope in Arizona. Known as SDSS J090745.0+024507, it is moving through the outskirts of the galaxy and is expected to leave our Milky Way galaxy within 80 to 100 million years. These stars are useful for astronomers to understand black holes and how our galaxy is made up, as during their lifetime, these stars travel across most of the galaxy. By measuring their movements, it is possible to learn more about the shape of the Milky Way and about the way its dark matter is distributed.
4- The Crab Nebula
Located in the constellation of Taurus, the Crab Nebula is the left over remnants of a supernova explosion. It is named such as the Irish astronomer Lord Rosse observed the nebula using his huge telescope at Birr castle in County Offaly and thought it looked like a crab and thus named it The Crab Nebula. The nebula is about 10 light-years across and was seen from Earth on 4 July 1054. It was called a “guest star” by Chinese astronomers and it was visible with the naked eye for 23 days in daylight and 653 nights before fading from view. The explosion that created the nebula was described as yellow in colour by Yang Wei-te, court astronomer to the Sung emperor. The reason I have it as one of my wonders is that this nebula is probably the most interesting nebulous object, as well as one of the most studied in all of astronomy. It is one of the most intricately structured and highly dynamical objects ever observed and personally I think it looks really beautiful.
3- Exoplanets Exoplanets or Extrasolar planets are planets outside of our Solar System. As of March 21 2011 there have been 531 confirmed discoveries. They are one of my wonders as it is hard to imagine when we look up at the stars in our night sky that there could be other worlds orbiting around them. Just imagine if there is a planet in the ‘Goldilocks Zone’ orbiting around another star i.e. it’s not too hot and not too cold, it is just right for life to exist then we may not be alone in the Universe after all. As of September 2010, Gliese 581 g, the fourth planet orbiting around the red dwarf star Gliese 581, is the strongest possibly terrestrial exoplanet orbiting in the habitable zone around its parent star and is currently being studied. Astronomers find locating an exoplanet rather challenging, as they do not emit as much light as stars, making them difficult to discover through telescopes. So astronomers use more advanced techniques such as looking for characteristic changes in stars and other astronomical phenomena which can be made by exoplanets. Occasionally, an exoplanet is found during transit i.e. when it passes in front of its parent star, briefly dimming the star’s light. The exact properties of many exoplanets are unknown, since it is difficult to observe details such as signs of life at such a great distance but most are believed to be giant gas planets like Jupiter. Scientists, however, hope to some day visit these planets for themselves. Click here to see if anymore Exoplanets have been discovered since the writing of this article!
2- Milky Way Galaxy The Milky Way galaxy is the home of our Solar System and is shaped in what is called a barred spiral. It contains anywhere between 100 to 400 billion stars with an estimated 50 billion planets, 500 million which could be located in the Goldilocks Zone. The Milky Way is part of The Local Group of galaxies and is one of around 100 billion galaxies in the observable universe. Wow…. With those big numbers out of the way I have put it at number two on my list of numbers because this is ‘our’ galaxy. An amazing fact is that when you look up at the night sky, every star that you see belongs to the Milky Way. We can usually see about 2,500 stars at any one time. In fact, the few thousand stars we are able to view with our naked eye are only about 0.000003% of the 200-400 billion stars that inhabit the barred spiral! The name of our galaxy comes from its appearance in our night sky. It refers to the milky patch of sky which rings the Earth. It was named in prehistory before anyone really knew what it was, so was just called the “Milky Way” for its appearance. You may have even seen it if you live outside of a big city or have very little light pollution, it looks almost like white clouds in the sky above us to the naked eye. It is visible during the summer month around the constellation on Sagittarius where we can view the center of our galaxy. An interesting fact is that the word galaxy comes from the Greek word, galactos for milk. The Latin version of Milky Way is Via Lactea, with “Via” meaning “Way” or “Road” and “Lactea” meaning “Milk”.
This has to be numero uno on my list of the wonders of the Universe. The Earth is the third planet out from the Sun and is our home planet. It is the only planet in our Solar System that we know of that can sustain life and the only planet that we know of that has liquid water on its surface. The distance the Earth is from the Sun is just perfect for our survival. A little further away or closer to the Sun and life would not be possible to exist here, aren’t we lucky? We are used to seeing images of the Earth, but it wasn’t until the twentieth century that we were able to really map our world when spacecraft and satellites took images of it from space. These pictures show us how truly amazing and beautiful our Earth is. We should really appreciate our world and how and why we are here! We can take Michael Collins’, one of the Apollo 11 astronauts, word for how beautiful the Earth looks from space!
(Article by Sinead McNicholl)