Cosmic "cannonballs" twice the size of Mars have been shooting out near a dying star, but no one knows where they are coming from, a new study revealed.

NASA's Hubble Space Telescope detected these superhot balls of gas zooming so fast through space every 8.5 years for the last 400 years.

The plasma balls detected by Hubble move so rapidly that it would only take at least 30 minutes for them to travel from Earth to the moon.

However, the findings present a challenge for astronomers: the cannon fire could not have been ejected by a nearby star known as V Hydrae, they said.

Where Did The Cannonballs Come From?

V Hydrae is a bloated red giant 1,200 light-years away from our planet. Red giants are considered dying stars in the final stages of life, exhausting their nuclear fuel.

Astronomers suspect that V Hydrae has likely discarded half of its mass into space during the star's "death throes." It has expanded in size and shed its layers into space.

Because scientists do not believe that V Hydrae could eject such balls of fire, the best explanation is that the materials were shot out by an unseen companion star.

The theory suggests that the companion star would have to be situated in an elliptical orbit that moves it close to V Hydrae's atmosphere every 8.5 years.

As the other star enters the red giant's outer atmosphere, it gobbles up the material, which then settles into a disk around the companion star. The disk serves as the launch pad for plasma balls that travel at approximately half million miles per hour.

Raghvendra Sahai, the study's lead author and an astronomer at NASA's Jet Propulsion Laboratory (JPL), says the light of V Hydrae is obscured about every 17 years.

Researchers say that because of the wobble of the jet direction, the plasma balls alternate between passing in front and behind the star system, hiding the dying star from sight.

Why Is The Discovery Important?

Sahai says the detection of cosmic cannonballs was the first time they witnessed the process. He said that it was quite pleasing as well because the research helped explain mysterious things observed about V Hydrae by other scientists.

"This discovery was quite surprising," said Sahai.

Sahai hopes the findings would be helpful in seeing structures in planetary nebulae. He and his colleagues also hope to use Hubble to further observe the V Hydrae star system.

Details of the new study are published in The Astrophysical Journal.