Few sights in the universe are more impressive than a dying star. The star expels its outer layers of gas, leaving only its small, hot core. Radiation from the core energizes that gas, causing it to glow in a rainbow of colors. It can look like a cat’s eye, a butterfly, an hourglass, or many other shapes.
Such an object is known as a planetary nebula. One of the closest and brightest is the Helix Nebula. It’s about 650 light-years away, in Aquarius.
It looks like a set of concentric rings. Filaments of cooler gas radiate out from the center like the spokes of a bicycle wheel. The spokes are behind “knots” of gas and dust that are as big as the solar system.
The Helix is shaped like a barrel, and we happen to be looking through the top of it. It spans almost three light-years.
The star’s core is becoming a white dwarf. Now, its temperature is about 200,000 degrees. It produces enormous amounts of ultraviolet light. It zaps atoms of gas in the nebula, making them glow. Each element shines a different color. Hydrogen and nitrogen are pink and red, while oxygen is green. The color palette helps us understand what was happening inside the star before it began exhaling its dying breath — forming the beautiful Helix Nebula.
The Helix is visible through binoculars and small telescopes. Tonight, it’s in the south after nightfall. It’s about half way between the planet Saturn and the bright star Fomalhaut, to Saturn’s lower left.
Script by Damond Benningfield