Space is a big place (Image: NASA/ESA/R. Humphreys)

See gallery: “Space superlatives: The universe’s extreme performers“

Biggest planet

Jupiter dominates the other planets in our solar system. Like all planets above a certain size, it is a gas giant made mainly of hydrogen and helium. The gassiest of all known gas giants, the unromantically named TrES-4, was discovered in 2006 orbiting a brightish star 1500 light years from Earth. Its diameter of about 1.8 times Jupiter’s makes it the largest accurately measured planet. Strangely, though, TrES-4 is very light for its size. It has only 88 per cent of Jupiter’s mass, giving it a density of roughly 0.2 grams per cubic centimetre, less than that of cork. Just how a planet can be as fluffy as TrES-4 remains a mystery.

Update: Science is never still in its pursuit of cosmic extremes: since this story was filed, new observations of the exoplanet WASP-17b suggest that it is even bigger than TrES-4b, with a radius almost twice Jupiter’s. The exoplanet is some 1000 light years from Earth and has a mass of just half Jupiter’s, making it an even fluffier mystery than TrES-4b.


Biggest artefact

Unless a giant alien monolith has appeared while this article was in press, the biggest known artificial structure in space is the International Space Station, 109 metres across and weighing 370 tonnes.

Biggest galaxy

According to the standard model of galaxy formation, the biggest galaxies are elliptical monsters formed from the collision of many smaller galaxies. The largest known example is the lens-shaped IC 1101, a billion light years away in the centre of the Abell 2029 galaxy cluster. IC 1101 is close to 6 million light years across, making it thousands of times the volume of the Milky Way.

Biggest hole

Not a black hole, for a change, but a vaster expanse of darkness. On the largest scales explored, galaxies are arranged into great walls and knots as much as a few hundred million light years across, with voids in between. The biggest known void – freakishly large at around a billion light years – was found in 2007. One outlandish suggestion is that it is a blemish left by an ancient close encounter with another universe.

Biggest star

A star called VY Canis Majoris, 5000 light years from Earth could swallow our sun 8 billion times over. Probably. Its estimated diameter of nearly 3 billion kilometres puts VY Canis Majoris in with a handful of stars that have earned the title red hypergiant. This estimate is contested, however, and some say the star is a mere red supergiant only 1 billion kilometres across.

Read more: “Extreme universe: Eight cosmic record-breakers“