Take a look at this picture.
If you're standing on the Earth's surface, that image covers a region of sky less than that of the moon. You could easily obscure it by holding a up finger at arm's length.
This tiny patch of starlight contains an estimated 10,000 galaxies, many of which are in their young, formative stages. The light from one of the galaxies has travelled from nearly the beginning of everything. Astronomers think they captured it just 450 million years after the big bang, which took place an estimated 13.82 billion years ago.
Now think about the rest of the sky. Pretty mind-blowing, isn't it? And utterly magnificent.
The universe is an amazingly vast place, and we know so very little about it.
We don't know why it exists, or the details of how it came into being. We don't if there's anything like us out there in the infinite vastness. We don't really know what black holes are. We don't know what dark matter is, the existence of which we can only extrapolate from its gravitational effects on the objects around it.
What we don't know about the universe is probably several magnitudes greater than what we do know, but we're finding out more all the time, mostly through advanced telescopes. These wonders of precision engineering allow us to peel back the layers of space and time to answer the greatest questions of the universe.
Peering into worlds unknown
There's a difference between what we can see from the telescope you set up at night on a grassy hilltop versus what you can see from a telescope that's already in space. That image above, for example, was taken by the Hubble Space Telescope, a reflecting telescope that orbits the Earth.
Getting a telescope into space gives it some very specific advantages. Have you ever seen how a straw appears bent or broken when you put it in a glass of water?
That's because the density change from air to water changes how the light refracts. The light bouncing off the straw slightly changes direction, which causes the illusion.
Light from cosmic objects does the same thing when it enters the Earth's atmosphere. Coming from space, which is comparatively low density, into the atmosphere changes the light's direction slightly.
Ground-based reflecting telescopes use lasers to create a false "guiding star" to correct for atmospheric refraction, and are usually located in very dark, non-urban areas, such as Mauna Kea in Hawaii and the Atacama Desert in Chile.
Space telescopes don't need to worry about this effect, because they're already out there. They also don't have the additional problem of light pollution from a nearby human presence.
Meeting Earth's match
I keep coming back to that same image above, because it's so utterly astounding. It isn't just a single, simple snapshot. Hubble's picture combines nine years' worth of data. For almost a decade, the Hubble telescope took repeated photographs of this tiny patch of sky located in the southern hemisphere in the constellation Fornax. The total of time the telescope spent imaging this patch of sky was 50 days -- an exposure time of 2 million seconds.
The light data from this two million seconds worth of exposure was then combined to create the 2014 Ultra Deep Field image, containing galaxies far, far too faint to be seen by the human eye. The faintest of the galaxies you can see in the image are one ten-billionth the brightness of what the human eye is capable of seeing.
One tiny patch of space. Ten thousand galaxies. Hundreds of billions of stars per galaxy. Per star, there is at least one planet. Although that number is probably much higher, given the size of our solar system.
The Kepler telescope, which is in orbit around the sun, has identified 1,030 confirmed Earth-like planets. These are planets that are similar to Earth in size, orbiting their star at a distance that would allow for the presence of liquid water, necessary for the formation of life.
Although the Kepler was crippled beyond repair in 2013, discoveries are still being made from the data it collected. In July 2015, NASA announced the discovery of Kepler-452b, the most Earth-like planet discovered to date. Think of every TV show or movie or anything that has ever explored the existence of life on other planets. We're now that much closer to finding out.
Kepler's amazing discovery of over a thousand more Earth-like planets doesn't even include the countless nebulas, the remnants of dead stars turned into birthing material for new stars; neutron stars; black holes; asteroids; comets; pulsars; cosmic rays; and the ever-elusive, ever-mysterious dark matter. In other words, worlds upon worlds.
Onward and ever upward
The Hubble Space Telescope has given us so much, but it's getting old, in telescope years. It turned 25 this year, and has been visited four times for servicing, the most recent of which was in 2009. From this point, it will continue to operate until its systems fail. In 2018, NASA plans to launch the James Webb Space Telescope to work alongside, then replace it. The James Webb Space Telescope will have a mirror 6.5 metres in diameter, compared to the Hubble's 2.4 metres.
Look again at this picture of a tiny patch of sky, which took so much technology to gather. I can't stop peering at the faintest spots of light, galaxies ancient and mysterious. It fills me with the strangest mix of emotions.
Elation, at how vast and beautiful is the universe.
Wonder at its deep mysteries.
Frustration that humans won't reach the distant stars in my lifetime.
Joy that our species is brilliant enough to create tools powerful enough to chronicle the sidereal realm.
And excitement at the rich and wonderful discoveries the future holds, thanks to those telescopes, and telescopes to come.