This beautiful image, showing an enormous bubble being blown into space by a young star, was chosen to celebrate the 26th anniversary of the Hubble Space Telescope. After so many stunning images captured by this exceptional satellite since its launch on 24 April 1990, it is difficult to surprise us. Like a soap bubble, the delicate Bubble Nebula is being blown into space by a super-hot star 45 times more massive that our Sun (located slightly off-centre on the upper-left side of the bubble). The strong stellar wind racing out at a speed of 6.4 million km/h sweeps up the cold interstellar gas in front of it, forming the outer edge of the bubble much like a snowplough piles up snow. Located in the constellation of Cassiopeia at a distance of 7100 light-years, the nebula has a diameter of seven light-years – which is about one-and-a-half times the distance from our Sun to its nearest stellar neighbour, Alpha Centauri.