But the real truth is that alien life on other planets could be even stranger than floating balloons or amorphous organisms ...

The spread of species beyond their native habitat is a human-made environmental change on a global scale. Among vascular plants, over 16,000 species have now permanently settled in foreign countries.

Many non-native plants could survive in the Arctic, as rising temperatures and human activity make it easier for invasive plants to arrive.

Socotra Island has been called the most alien-looking place on Earth, and with good reason. Sitting off the coast of Yemen in the Arabian Sea, it’s home to plants and landscapes found nowhere else.