The Galactic Center: The "Bar"

The closer you go to the center of the galaxy, the more stars there are, and the more densely packed they become. To show this would have required planting foliage so densely that it would not be possible to go to the center, so we have not shown most of them.

Instead, there are two very important and recently discovered features there. The first is the so-called "bar". Astronomers have long noticed two distinct types of spiral galaxies; "normal" and "barred".

Spiral Galaxy M81.
In the "normal" type, the spiral arms wind all the way into the center of the galaxy, such as in spiral galaxy M81.

Barred Spiral Galaxy NGC1300.
In "barred" spiral galaxies, the arms wind down to a straight feature that cuts across the center, called the bar, traced out in dark dust, as in barred spiral galaxy NGC 1300.

It was only in the last few decades that the work of Leo Blitz and other astronomers revealed the presence of a bar in our own Milky Way.

Galaxy Garden Bar.
In the Galaxy Garden, we depict this bar by a stone oval of the right size and orientation. It is pointed almost directly at the solar system, so we see it end-on, which was one reason it was difficult to discover.


The Galactic Center: The Black Hole



One of the most important recent discoveries about galaxies is that many of them include a supermassive black hole at their center. We have seen evidence for them in other galaxies and evidence for one in our own Milky Way. In some sense, the black hole may have been the seed that enabled the galaxy to form, though it has certainly grown much larger since its original formation.

Black holes are among the most enigmatic and fascinating objects ever imagined, so incredible that it is hard to believe that they really exist. But the evidence for their existence is strong.

The black hole at the galactic center has the mass of millions of stars like the Sun, yet it is very compact for such a huge mass; hardly larger than our solar system. It is far too small to be seen in the Galaxy Garden, just as the actual solar system would require a microscope to resolve.

But because of its importance, and the great popular interest in it, we have enlarged the black hole more than a million times, and created a fountain to symbolize it.

Close-Up of Fountain.
The outer wall defines the area most affected by the black hole; a disk of material that feeds it, symbolized here by the pond. The black hole itself is suggested by the depiction of the "gravity well" often used in science diagrams to represent the black hole. The reflection of the gravity well suggests the bi-polar nature of the black hole (material can fall into it from both sides of the galactic disk).

Black Hole.
When the fountain is on, a circular "event horizon" appears in the disk. This marks the point of no return, where material is inexorably drawn into the black hole.

Black Hole Labeled.
Some of the material drawn into the black hole is ejected like a jet of water, spraying our perpendicularly both above and below the disk. When you place yourself in the exact right spot, you can see the reflection of the jet going correctly in the opposite direction of the real jet.

The Garden is now open to the public and welcomes all visitors to the Big Island.

Click here for information on how and when to visit the Galaxy Garden.

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