Did Venus 'swallow' its own moon?

Scientists have come up with a surprising new theory about one of our neighbouring planets - and it involves a missing moon.

They think Venus may once have had one, but that it slowly moved closer to the planet, before eventually crashing into it.

The idea could help explain why Venus doesn't have a moon today, although experts can't say for sure that one ever definitely existed.

So, what could have happened? Keep reading to find out.

The research was carried out by scientists at the University of California, Riverside, in the US.

They decided to take a closer look at why Venus - the planet most like Earth in size - doesn't have a moon of its own.

They wanted to see whether the planet's very slow spin could be the reason why.

Using computer models, they explored what would happen to moons of different sizes as they orbited the planet.

The team found that, sooner or later, regardless of their size, the moons would likely move closer to Venus before eventually colliding with it.

Lead author of the study, Stephen Krane, explained: "If [Venus] had a moon, and it likely did at some point, it could not have kept it.

"That moon would have crashed down on the planet in a relatively short time scale."

The team think this could have happened within the first billion years of Venus' history, around 4.5 billion years ago.

However, it's important to remember that researchers haven't yet been able to prove whether Venus definitely ever had a moon.

Scientists have previously suggested that it may never have had one, or that a moon could have been destroyed in a massive collision with another space object.

Experts hope to find out more about Venus with two future planned Nasa missions, called DAVINCI+ and VERITAS, which will study the planet's atmosphere and geologic features.

1. Venus is the second planet from the Sun - about three quarters of the distance between the Sun and Earth.

2. The planet is often referred to as 'Earth's twin' because they both have very similar sizes.

3. Venus is the hottest planet in our solar system with an average temperature of 460°C.

4. Venus has a thick atmosphere which acts like a blanket trapping the Sun's heat inside. Its surface is dry and rocky with lava flows across parts of the planet.

5. It takes Venus 243 Earth days to spin round on its axis but only 225 days to complete an orbit of the Sun. So a day on Venus is actually longer than a year!