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How big is a Gigaparsec?

A Gigaparsec is 33 yottametres

An Infinite Journey Into Gigaparsecs

Have you ever looked up at the night sky and wondered just how far those twinkling stars are from us? Or how vast is the universe itself? The answer is mind-bogglingly huge, so huge that we have to use special units, like Gigaparsecs, to even start to comprehend it.

What is a Gigaparsec?

In the world of astronomy and astrophysics, distances are so enormous that our usual units of measurement, like miles or kilometers, just don’t cut it. That’s why scientists use parsecs. A parsec is the distance at which one astronomical unit (the distance from the Earth to the Sun) subtends an angle of one arcsecond. It’s about 3.26 light-years or 19.2 trillion miles! But when we’re talking about the most distant objects in the universe, even parsecs are too small. For these colossal distances, we need Gigaparsecs. A Gigaparsec (Gpc) is one billion parsecs!

Size Comparison: Gigaparsec and the Universe

To get an idea of how big a Gigaparsec is, let’s compare it to some things we might be more familiar with:

  • One Gigaparsec is about 3.26 billion light-years. That means, if you could travel at the speed of light (which is a whopping 670,616,629 miles per hour), it would still take you 3.26 billion years to cover one Gigaparsec!
  • The observable universe, the part of the universe we can see from Earth, is about 93 billion light-years in diameter. That’s almost 30 Gigaparsecs!
  • The distance to the farthest known galaxy, GN-z11, is about 13.4 billion light-years. That’s a bit over 4 Gigaparsecs!

Understanding Gigaparsecs

A Gigaparsec is so vast that it’s hard to wrap our heads around it. But here are a few fun facts that might help:

  • The term parsec is a combination of two words: parallax and second. It was coined by British astronomer Herbert Hall Turner in 1913 to simplify astronomical distance calculations.
  • While parsecs are used for measuring shorter distances within our galaxy, the Milky Way, we need kiloparsecs (thousands of parsecs), megaparsecs (millions of parsecs), and Gigaparsecs for larger cosmic scales.
  • Many quasars, the brightest objects in the universe, and the most distant galaxies, are several Gigaparsecs away from us.

Gigaparsecs and Beyond

In the grand scheme of the universe, even a Gigaparsec is not the end. The universe is vast and ever-expanding, constantly pushing the boundaries of our understanding. So the next time you gaze up at the night sky, remember: those tiny points of light are not just far away, they’re Gigaparsecs away! In conclusion, Gigaparsecs provide us a way to measure and understand the vastness of the universe. It’s a unit that reminds us of how tiny we are in the grand cosmic scale. It’s a testament to our human curiosity and desire to comprehend the infinite universe around us. Gigaparsecs, the universe, and all of its wonders await our exploration! It’s a journey of a billion parsecs, a journey into the infinite depths of the cosmos, a journey that begins with a single star and stretches on forever, one Gigaparsec at a time.

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Eridanus Supervoid
It's a region in the night sky that's slightly cooler than the normal CMB temperature. It's 2.7 K, or -270.5 °C. Barely above absolute zero. One hypothesis says it leads to a parallel universe. Whoa!
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The Great Attractor is pulling thousands of galaxies, including the Milky Way, towards itself. Its mass is tens of thousands of times greater than the Milky Way's.
Larger By Category
Hercules–Corona Borealis Great Wall
The Hercules–Corona Borealis Great Wall is the largest known structure in the universe. It is made up of galaxies, and is called a galactic filament. We are not in it. In fact, it lies about ten billion light-years from us.
Distance to the HDF
The Hubble Deep Field is a picture of an empty spot in the night sky. The image had almost 3,000 objects in it - distant galaxies. It's unknown where these galaxies are now, but where they were 12.7 billion years ago is 12.7 billion light-years away from us.
Observable Universe
The radius, which is half of the diameter, is about 46 billion light-years. You might expect to only see 13.7 billion light-years away because light has had only 13.7 billion years to travel, but due to the expansion of space, the objects that used to be 13.7 billion light-years away are now 46 billion light-years away, and we can see these.