NASA’s Astronomy Image of the Day, May 29, 2023: The Milky Way and the Biosphere

Our solar system, with the sun at the center and 8 other planets besides the earth, is located in a mysterious part of the galaxy called the Milky Way. It is a spiral galaxy that spans about 100,000 light years and formed about 14 billion years ago. According to NASA, there are more than 100 billion stars in the Milky Way, and they all orbit the supermassive black hole at the center of the galaxy, which is estimated to have a mass four million times the mass of our Sun.

Today’s NASA Astronomy Photo is a breathtaking snapshot of the Milky Way taken above the bioluminescent sea of the Maldives. What is the turquoise glow in the water? It is caused by a single-celled plankton known as Noctiluca scintillans, which ignites when stimulated by ocean waves to keep predators away. The sky is dominated by the Milky Way and the constellation Omega Centaurus on the left and the Southern Cross star in the middle. The picture was taken by astrophotographers Peter Horalek and Sofina Jani.

NASA description of the image

What’s on fire there? The answer depends: sea or sky? The unusual blue glow in the sea is bioluminescence. In particular, the luminescence comes from Noctiluca scintillans, which are unicellular plankton stimulated by rolling waves. Plankton use their glow to attract and illuminate predators. This display in mid-February on an island in the Maldives was so intense that an astrophotographer called it a turquoise wonderland. Instead, there are more frequent flares of stars and nebulae in the sky.

The white band rising from the artificially lit green vegetation was created by the billions of stars in the central disk of our Milky Way galaxy. Also visible in the sky is the constellation Omega Centaurus on the left and the famous Southern Cross star in the middle. The red-glowing nebulae include the bright Carina Nebula, far right in the center, and the huge Gummy Nebula in the upper right corner.