The biggest object in our solar system is Comet Holmes - at least temporarily. This comet performed an outburst on October 24, 2007 and since then it has expanded enormously.
Astronomers from the University of Hawaii report the halo around Holmes' tiny 3.6km nucleus now measures more than 1.4 million kilometers!
Comet Holmes made its spectacular outburst on October 24, 2007. Formally dim enough to only be visible in the most powerful telescopes, it quickly brightened up to be seen with the unaided eye - even in light-polluted cities (like my very own Vancouver).
Astronomers from the University of Hawaii's Institute for Astronomy recently measured the halo surrounding Comet Holmes to be 1.4 million kilometres (0.9 million miles). And as I mentioned in the opening paragraph, that makes it larger than the Sun. Of course, it's just a thin halo of gas and dust particles, but still, that's pretty impressive.
Just to get a sense of the change, Holmes has brightened by a factor of 500,000x. All this gas and dust is pouring out of a tiny nucleus only 3.6 km (2.2 miles) in diameter.
Astronomers say the comet's halo may grow even larger and hope it will outburst a second time like it did in 1892.