8. Boötes（The Herdsman）

Boötes

The Herdsman

Vortex

Barnard 68（ESO; European Southern Observatory）

  Sisask's image for the constellation Boötes is "Vortex."

  Why "vortex"?   I pondered for a long time about why this piece evokes such a musical atmosphere. In the end, I considered two possible explanations.

  The first explanation.  This one is rather difficult to articulate.

   There is a region in the area of Boötes known as a "supervoid," a part of space where no galaxies exist. This discovery was made in 1981, right around the time Sisask was composing "The Starry Sky of the Northern Hemisphere." At that time, new hypotheses were being proposed regarding the structure of the universe. In space, there are regions where galaxies are densely clustered, such as galaxy clusters and galaxy groups, but there are also regions where there is almost no matter at all. The completely black areas in the image above are called "dark nebulae," which are clouds of interstellar gas and dust that do not emit light, and they contain almost no stars.　

　

   In the direction of Boötes, there is a region 300 million light-years away where galaxies are absent for a distance of 150 million light-years. This region is known as the "Boötes Void." This discovery led to the idea that the universe has a structure similar to soap bubbles. The concept is that the universe resembles the multi-layered bubbles formed when you froth up soap, with galaxies dotting the surfaces of the bubbles, while the hollow interiors of the bubbles are empty of galaxies. Of course, these "bubbles" are on an enormous, cosmic scale!

   Based on this, it’s possible that Sisask imagined viewing the swirling motion of countless galaxies on the "surface" of the bubbles, while looking outward from within the void. In the context of the image above, imagine standing inside the pitch-black area (not a flat surface, but a hollow space) and looking around 360 degrees at the dense stars and galaxies surrounding it. (For reference, the image is of Barnard 68, a dark nebula in the direction of the constellation Ophiuchus, so it’s used here only as an illustrative example.)

   This idea occurred to me while listening to his music. Sisask's music for Boötes sounds just like bubbles bursting. The interwoven movements evoke an image of a mesh-like structure, which also reminds me of foam. However, in the context of space, the "bubbles" are not the same as soap bubbles. The "bubbles" in space are composed of countless stars and galaxies scattered across vast distances. Seen from a distance, these bubbles might appear to merge into one large "vortex." While Sisask's Boötes is not necessarily a large-scale composition, imagining these cosmic phenomena allows us to appreciate the mysterious nature of the universe.

   The second point.  We cannot overlook Arcturus, the bright orange first-magnitude star in the constellation Boötes.

A Spectacular Sky Over the Grand Tetons

　

   This beautiful photo features the Rocky Mountains and a starry sky. The Milky Way Galaxy rises on the left. Shining on the far left edge of the mountains is Jupiter. The bright star near the center of the photo is Arcturus, the first-magnitude star in the constellation Boötes. The Big Dipper can be seen on the far right of the photo.

   Arcturus is a star whose name means "Guardian of the Bear" in Greek, and it emits 100 times the light of the Sun. While stars are generally said to be "fixed" in the sky, they are, in fact, slowly moving along with the rotation of the galaxy. However, Arcturus does not follow this rotational motion; instead, it moves at a right angle to it. Moreover, it is moving at the astonishing speed of 140 km per second. That said, to the naked eye, it would take about 800 years for its apparent position to shift by the width of the Moon, so we are often amazed by the scale of astronomical figures. Arcturus is also one of the stars that form key patterns in the night sky, such as the Spring Arc, the Spring Triangle, and the Spring Diamond.

   It might be difficult to extract the image of a "vortex" directly from Arcturus, but the fact that Arcturus is moving at such an incredible speed could have provided Sisask with enough musical inspiration to create something interesting in his composition for Boötes.