Every now and again, we get a little glimpse of just how far human ingenuity has gone.
Quite literally: The above image was taken by a spacecraft travelling through the Solar System while it was at a distance of 251 million kilometres (156 million miles) from Earth – more than the distance between Earth and the Sun by nearly half again.
It was snapped by NASA and the European Space Agency's Solar Orbiter, a mission to study the Sun, on 18 November 2020, while en route to its destination. It joins a burgeoning tradition of photos of Earth taken by instruments far beyond where humans ourselves can venture.
But it's not just Earth in Solar Orbiter's image; Venus and Mars make an appearance, too, 48 million and 332 million kilometres from the spacecraft, respectively. It's a lovely family portrait when you think about it – three rocky planets, so similar in many ways, but so very different from each other – seen through a scientific instrument – the Heliospheric Imager – designed to study the heart of the Solar System.
(ESA/NASA/NRL/Solar Orbiter/SolOHI)
The Solar Orbiter launched in February 2020, and its flight was planned to make several Venus flybys to take advantage of the planet's gravity for a speed boost, a manoeuvre known as a gravity assist. The image of the planets was taken as the Solar Orbiter was moving towards Venus for one of these flybys.
By the time Solar Orbiter arrives in position around the Sun to start operations in November 2021, it will be swooping far outside the planetary plane to glimpse the Sun's polar regions. This will be tremendously exciting since, due to our vantage point on Earth, we've never directly imaged the Sun's poles.
While it is in transit, the Solar Orbiter is making observations. This helps the Solar Orbiter team back here on Earth calibrate and test the instruments on board, but that data can be used for scientific analysis, too, of planets, of the solar wind, of space weather.
It gives us a little inspiring reminder, too, of the fragility and resilience of our own existence. Such photos always call to mind the words of Carl Sagan, in his 1994 book Pale Blue Dot, of a photo of Earth taken by Voyager 1 on its way out of the Solar System.
"Look again at that dot. That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives," he wrote.
"The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilisation, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every 'superstar,' every 'supreme leader,' every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam."