You don’t have to actually see something to know it’s there. You might feel it, hear it, or smell it. In other words, you use all your senses to suss it out.

Astronomers do that all the time. They may not see a star through their telescopes, for example, but they know it’s there because they use all their senses – special instruments that “see” what the eye cannot.

An example is Regulus, the brightest star of Leo. What we see as Regulus looks like a single point of light even through the largest telescopes. But instruments attached to those telescopes reveal a second star.

The instruments spread the light from the system into its individual wavelengths or colors – a spectrum. Each chemical element imprints a unique pattern in the spectrum. But Regulus shows two sets of those lines. And over time, the patterns move back and forth. That means Regulus has a companion just a few million miles away. The two objects orbit each other once every 40 days.

The companion is a white dwarf – the corpse of a once normal star. It’s much smaller and fainter than the system’s main star, and the two stars are quite close together. That makes it impossible to see the white dwarf through the glare. But we know it’s there – thanks to the extended senses of astronomy.

Regulus is quite close to the full Moon as night falls this evening. The Moon moves away from Regulus during the night, but they’re still close at dawn.

Script by Damond Benningfield