Betelgeuse, one of the brightest stars in the sky, will almost disappear next week. Here's how to see it.

• Betelgeuse, one of our brightest stars, will almost disappear on December 12. 
• This is due to a "once a lifetime" event of an asteroid blocking the star's light. 
• Amateur astronomers could watch the event themselves, and provide valuable data for scientists.

Betelgeuse, one of the most visible stars in our skies, has been behaving strangely over the past few years.