An exo-moon that’s as big as Uranus! But it ain’t Endor

This week’s news that the first exo-moon might have been found, about 4000 light years away, is startling for several reasons. The first astonishing bit is that it was found at all. The majority of planets orbiting other stars have been found by light-curve analysis as the planet passes directly between the parent star and … More An exo-moon that’s as big as Uranus! But it ain’t Endor

New Horizons and Ultima Thule – the bonus mission

On 1 January 2019 the New Horizons probe – the one that whipped past Pluto in 2015 – will encounter another outer solar-system body: 2014 MU69. Informally it’s become known as Ultima Thule. The neat part is that this body wasn’t even known when New Horizons was launched in January 2006. Back then, the probe … More New Horizons and Ultima Thule – the bonus mission

How GPS finds you and lets Google send you adverts

If both Special and General Relativity didn’t work precisely as Einstein said it did, GPS would be far less accurate than it actually is. Like, way off, meaning those auto-drive cars wouldn’t even get to the right road. Or any road. And we’d all be lost. Let me explain. GPS works by very precise distance … More How GPS finds you and lets Google send you adverts