A giant gas cloud could produce a massive burst of huge new stars when it collides with our galaxy, scientists say.

The Smith cloud, made up of hydrogen gas, is heading towards the Milky Way at 1.1 million kilometres an hour.

"Its shape, somewhat similar to that of a comet, indicates that it's already hitting gas in our galaxy's outskirts," says astronomer Felix Lockman. Photo: BILL SAXTON/NRAO/AUI/NSF

Measuring 11,000 light-years long and 2500 light-years wide, it was only 8000 light-years from us.

It would strike the Milky Way at an angle of around 45 degrees.

"The leading edge of this cloud is already interacting with gas from our galaxy," says Felix Lockman, leader of a team of astronomers who was studying the cloud.

When it collided, it could create up to 2 million new stars.

"Many of those stars will be very massive, rushing through their lives quickly and exploding as supernovae.

"Over a few million years, it'll look like a celestial New Year's celebration, with huge firecrackers going off in that region of the galaxy.”

But don't put the house on the market just yet - the cloud is due to hit in about 30 million years.

"Its shape, somewhat similar to that of a comet, indicates that it's already hitting gas in our galaxy's outskirts.

"It is also feeling a tidal force from the gravity of the Milky Way and may be in the process of being torn apart,” says Felix.

While scientists had been tracking the cloud for decades, they had only recently discovered its chemical composition.

And strangely, the make-up of the cloud showed it may have come from the Milky Way in the first place, before being ejected.

"This is most likely a gas cloud left over from the formation of the Milky Way or gas stripped from a neighbour galaxy.”

-Stuff.co.nz