The visitor from deep space has passed us by, but may be due for an outburst as it careens toward the sun.
The object, known as Comet Swan, was discovered by an instrument floating in space: Nasa and the European Space Agency’s Solar and Heliospheric Observatory, or SOHO, satellite.
As it gets closer, the comet should be visible in the Southern Hemisphere just before sunrise, without any equipment. Comets rare enough to be seen without needing to use a telescope are rare,
The show could be seen in the coming weeks, becoming most clearly visible at the end of May and beginning of June.
Comet Swan came closest to Earth on 13 May, when it will swing by around 53 million miles away. It will then carry on to get closer to the Sun on 27 May, before sailing back off through the solar system.
The behaviour of comets is notoriously difficult to predict, especially as they fly closer to the Sun. Just weeks ago, starwatchers had been hoping to get a glimpse of the comet Atlas as it headed past Earth – but it broke up on its way, leaving a series of impressive if somewhat tragic photos.
As comets get nearer to the Sun, and the temperature gets hotter, they tend to heat up and start shedding material in a dust trail that can be visible in images. The ice, dust and rock that makes up a comet can then break up or become more visible, and it is difficult to know how any given object will behave in the circumstances.
The Comet Swan was first spotted last month, by an amateur astronomer called Michael Mattiazzo. He saw it in data from an instrument on the SOHO satellite called Solar Wind Anisotropies or Swan, which gives the object its name.