Etikettarkiv: earth

Perspective: How large is a solar flare?

Astronomy is awesome greatly due to its huge size. It is impossible for any human being – a brilliant scientist or a regular Joe alike – to wrap one’s mind around how big space really is, how tiny we humans really are on our little rock in the blackness of cosmos.

A solar flare is a sudden release of large amounts of energy from the Sun, causing what is basically a huge storm pulling up from the Sun surface. Seeing as the Sun is so big itself it is hard to visualise how big a solar flare really is – it looks rather tiny in comparison.

Well, the Earth is fairly tiny in comparison to the Sun to. And a solar flare is huge. Just look at the amazing photoshop above of how tiny Earth would seem in comparison to a striking solar flare.

Star greater than the Milky Way?

At a party a few days ago, I was standing outside with a couple of friends viewing the incredible night sky when we started talking about the magnificent vastness of space. One of them brought up having heard of a single star that was greater than the entire Milky Way galaxy – which is pretty freaking huge! I was skeptical, seeing as from what I know of stars there is a top limit of both mass and size, when the star will collapse onto itself, exploding into a supernova. Stars can be incredibly huge, but as large as the Milky Way, which itself contains several hundred billion stars?

See the Earth dwarfed by our Sun, and it dwarfed by the ginormous VI Canis Majoris, the greatest star discovered. (ill. D. Jarvis)

Stars can indeed be pretty huge, but it’s impossible to keep track of the big numbers. The standing fact, I confirm after a few minutes of researching, is that while stars are huge, the galaxy is a lot huger. In the end it’s like comparing an A2 poster to North America – surely a poster can be pretty big, but an entire continent plays in a different league altogether.

Our own star, the Sun, is about 1 392 000 km in diameter, 109 times the size of the Earth. That’s a tad smaller than your random star in the universe, and there are lots of different kinds of stars both smaller and greater. Our Sun is very much a dwarf, and there are many stars that are several orders of magnitude larger. The greatest star discovered in the universe is VY Canis Majoris, a red hypergiant 2000 times the size of the Sun!

Our Sun as compared to the largest known star. (ill. Mysid)

That’s large. That’s large enough to stretch through a great deal of our solar system. If VY Canis Majoris for some reason suddenly replaced our star, the entire Earth would be engulfed in its flames, as would Mercury, Venus, Mars, the Asteroid Belt, Jupiter and Saturn. Cool, but not nearly as big as the galaxy – that’s several hundred billion times larger.

Illustrations: ”Comparison stars and planets” by David Jarvis (CC BY-SA 3.0), ”Sun and VY Canis Majoris” by Mysid (public domain).

The Beautiful Cosmos: Jupiter and Io

When talking astronomy pictures, it’s difficult to say which pictures  are ”real” and which ones are not. A great deal is obviously just computer generated or hand drawn, but the ones I post as part of the Beautiful Cosmos blog series all have some degree of validity to them. The first problem that crops up is simply that as soon as you get a photo from some distance (from a good telescope or a probe) the light you catch is not just visible. Most astronomy pictures try to represent the many variations of colours that the human eye simply isn’t capable to capture or comprehend.

Jupiter and Io as captured by NASA's New Horizons probe in 2007. Click to embiggen.

A problem is that we can’t really estimate the exact colours of nebulae, supernovae and galaxies when they are basically impossible to see on close-up without… you know, dying. So the basic answer to how for example a nebula would look from just a couple of light years is… you wouldn’t see it. It’s surrounded by clouds of dust blocking vision and – again – killing you. The best the astronomers can do is a rough estimate.

When it comes to planets and moons, it’s a little different. Almost all pictures of moons (including our) and the planets (including Earth) that you’ll see, including ones I post, are composites of several different pictures, sometimes just a couple and sometimes several dozens. That doesn’t make it the less real, it just allows for much higher precision than if you took a photo of the entire planet at the same time. The end result is basically how it’d look in real life. To me, this is real enough.

A great deal of high-detail photos that include several objects (such as a planet and its moon(s)) are ”fake” in that they are composited of different pictures. All photos you have ever seen of several planets (close up) at the same time are totally fake. Planets simple aren’t close enough, and photographing two planets in our solar system together is akin to photographing two flies on opposite sides of a football field. Obviously it can be done – planets like Venus, Jupiter, Uranus and Mars can all be viewed simultaneously on Earth’s night sky – but they won’t be in such high detail.

This picture, of Jupiter and it’s moon Io, is both real and fake. It’s all real, but the Jupiter part is made up of three composites, and the Io part is taken at a different time and then added. Still, they seem to fit in proportion, and from the right angle this is just as awesome as it would look. Read more about the authenticity of this particular picture on the Bad Astronomer Phil Plait’s blog.

The Beautiful Cosmos: Aurora Borealis from Space pt. 2

My old post with a photo of aurora borealis as seen from the International Space Station (ISS) really is nothing in comparison with this new 30-second video. The ISS is filming from above Canada, with the awesome green light reflections shimmering beneath.

The Beautiful Cosmos: Aurora borealis from space

This is an amazing picture taken by the good folk at the International Space Station (ISS) earlier in February. Moving at such a great speed, the ISS crew experiences a total of 16 Earth dawns every day, constantly catching up with the Earth time zones. The green and blue lights at the Earth horizon is the fantastic aurora borealis, the northern lights, which were especially active this February. Watch this and more photos of Earth from space at Flickr.

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My first go at telescope photography.

Almost every night I am shocked that there’s a huge rock floating in the sky, clearly visible with the naked eye yet thousands of kilometers away. The Moon continue to capture my interest, on most nights more so than the most fantastical clusters, stars and nebulae. There is a reptilian part of my brain – in all of our brains – that still refuse to grasp the existence of the world out there, the beautiful, magnificent, ever expanding cosmos surrounding us, marking out our insignificance, turning us into a speck in the sea of darkness.

But the Moon is there. It is inescapable. It has always been there, as long as there have been humans, and it will probably remain until the last human either dies on Earth, or leaves Earth to be swallowed by the Sun. The Moon is there. And we have been there.

And I keep feeling that the giant ball in the sky is worth some extra thought in these clouded nights.