This week’s news that Voyager 1 has left the solar system is pretty cool.

Actually, not just cool. Totally awesome.  JPL scientists were able to use Voyager’s ‘plasma wave’ instrument to measure oscillations in plasma around the probe, giving its density; and this week, the plasma science team at the University of Iowa analysed the data and confirmed that the probe had entered interstellar space.

The important part is what it means. For the first time in the 4.6 billion year history of our world, something from Earth has left the solar system.

It is the stuff of dreams.

Not bad for a space probe launched when trousers were flared and disco was in. The day was 5 September 1977. With its twin, Voyager 2, the 770kg probe was the low-budget reality of a ‘grand tour’ that fell victim to post-Apollo penury. And once their Titan-Centaur boosters had exhausted their…