To answer that question, we need to know their sizes and distances. To gauge how large these things appear in our sky, we can take the ratio of these things' sizes to their distances. But don't take out your calculators yet. Before you start punching in numbers with lots of zeros, you should first do a mental reality check on their order-of-magnitude proportions.
It's important to do a reality check like this first, because when you're dealing with very large or very small numbers, forgetting to punch in one zero in your calculator can majorly affect the outcome of your calculations. Now that we've done that, we can plug in the actual numbers. How well should Hubble see either the galaxy or Pluto? To answer this question, you need to know the angular resolution of Hubble's camera. Look up its angular resolution and you'll find out that it is 0.
Category: Space Published: October 23, Strictly speaking, when telescopes look at the light from distant galaxies, they are not literally looking back in time. The past no longer exists, so no one can directly look at it.
Instead, the telescopes are looking at the present-time pattern of a beam of light. Since the beam of light has been traveling through the mostly-empty vacuum of space for millions of years, it has been largely undisturbed.
Therefore, the present-time pattern of this beam of light is the same as the pattern that it had when it was first created by the distant galaxy millions of years ago. By looking at the present-time state of a beam of light, we can thus infer what the galaxy that created the light looked like millions of years ago.
This is potentially quite exciting, isn't it? We're in the future! We could tell the sun who's going to win the World Series eight minutes before it finds out and make millions of dollars in solar gambling. Unfortunately, we're not experiencing the thrills of the universe before anybody else. Rather than us getting a glimpse of the future, we're actually just too far away to see what's happening right this second to the sun.
It all comes down to light and how quickly it gets to us. Light travels at , miles , kilometers per second [source: Russell ]. In technical science language, that is fast as all get-out.
It's so fast that when we switch on a lamp at home, we never have to "wait" for the light — or, more precisely, the light is so very close to us that the time it takes to reach us proves negligible. But the sun's rays — 92 million miles million kilometers away from us — still have to sprint quite a distance to us before they make it to Earth. The name Population I had already been taken when astronomers classified the stars of the Milky Way as Population I stars like the Sun, which are rich in heavier elements.
Then, the name Population II was used to classify older stars in the Milky Way with a low heavy-element content. And that left the name Population III to classify the stars that were forged from the primordial material that emerged from the Big Bang , approximately Population III stars must have been made solely out of hydrogen, helium and lithium, the only elements that existed before processes in the cores of these stars could create heavier elements, such as oxygen, nitrogen, carbon and iron.
Rachana Bhatawdekar of the European Space Agency led this most recent study, probing the early Universe from about million to 1 billion years after the Big Bang.
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