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SPACE-TRIANGULUM-GALAXY-MESSIER 33

Do you remember being very young and beginning to discover how where you lived fit into the world? Maybe you realised the number on your front gate was part of your address, or found that the street you lived on was one of many streets in a suburb, and that suburb was in a city with thousands or even millions of people. Perhaps you saw Australia on a world map for the first time, and could see its relation to other countries – didn’t it look far away from anywhere else?

In time you learned that you were on a planet called Earth, and when you were taught about the solar system, discovered that the Earth was really quite small, and a long, long way away from other planets. And that we all revolved around a Sun which was a star, not a very big one, and one of around 100 thousand million in the Milky Way – one of more than a 100 billion galaxies in our universe.

I don’t know about you, but when I learned all this in astronomy class, it totally blew my mind. The same way it blew my mind when I was a toddler and began to gradually understand that our farm was one of many in our hamlet, and that we were all part of a town 25 km away, and the regional centre was 50 km away, and the state capital 300 km away, and the nation’s capital a great distance, and the next country even further than that, across the sea. It made me feel very small and a long way from everything.

And when you were little, did you ever write down your address in this fashion: My Bedroom, 11 Acacia Road, Seaforth, Manly, Northern Beaches, Sydney, Cumberland County, New South Wales, Australia, Oceania, Southern Hemisphere, The Earth, The Solar System, The Milky Way, The Universe? Now there’s an another element to add to the address.

Astronomers have known for ages that the Milky Way is part of a larger cosmic structure, but it was too hard to figure where one group of galaxies ended and the next began. Recently a team of astronomers at the University of Hawaii, led by Brent Tully, have gathered measurements allowing scientists to define superclusters of galaxies. Their work, published this month in Nature, describes the vast group of galaxies to which the Milky Way belongs.

The name of our particular galactic supercluster is Laniakea, which is 520 million light years in diameter, and contains one hundred million billions Suns spread across 100 000 galaxies. The Milky Way is right on the fringes of Laniakea, on the edge of a vast empty region of space known as the Local Void, but we are constantly pulled towards a gravitational force in Laniakea’s centre which scientists have dubbed The Great Attractor.

Within the Laniakea Supercluster, we are part of the Virgo Local Supercluster, and beyond it are the neighbouring superclusters of Hercules, Coma, and Perseus-Pisces. Just as with the original problem of defining the edges of galaxies, it is not yet clearly known where the edges of Laniakea end and the edges of these other superclusters begin.

One surprise was that the Laniakea Supercluster is being pulled by a larger concentration of galaxies called the Shapley Supercluster, so we may be part of even greater structures that are yet to be discovered. Thus our universe expands as knowledge and comprehension grows.

Brent Tully, who has helped create our new map of the Milky Way’s environs, says: Seeing a map gives you a sense of place. For me, having that sense of place and seeing the relationship of things is very important in terms of understanding it. Thanks to Tully and his team, we have gained another insight into our place in the universe – and how small we are, and what a long way from everything.

The name Laniakea was suggested by Nawa’a Napoleon, associate professor of Hawaiian Language at Kapiolani Community College. The Hawaiian name can be translated in a number of ways, including “open skies”, “wide sky”, or “wide horizons”, but in this case it is understood as “immeasurable heavens”. The name was chosen to honour Polynesian navigators who studied the heavens in order to navigate the Pacific Ocean.

Laniakea is pronounced LAN-ee-uh-KAY-uh in the video from Nature I watched, although I have seen it written as la-NEE-uh-KAY-uh. It is well known in Hawaii, as it is the name of a surf beach famous for its sea turtles, and the name has been used for numerous businesses in the area. It does get very occasional use as a personal name, and although it is technically unisex, seems to have only been given to girls. Lani, Nia, and Kea are the obvious nicknames.

This is an elaborate Polynesian name which is unusual, but seems very usable in Australia, which has a significant Pacific Islander population, and where several Polynesian names are familiar. The short forms are very much on trend here.

While Laniakea has had some use as a Hawaiian name for girls, Hawaii has shared the name with the whole planet, and it now belongs to all of us. It’s not just a beautiful beach on the shores of a great ocean, but a multitude of galaxies whirling through the immensity of space, the “immeasurable heavens”. And it is our home.

POLL RESULTS
Laniakea received a very good approval rating of 72%. People saw the name Laniakea as beautiful or pretty (21%), having a cool cosmic connection (20%), and having a fantastic meaning (19%). However, 15% of people thought it was too long and complex. Only one person thought the astronomical background made the name Laniakea seem geeky.

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