This is the most modern space related stamp I have though I also have several stamps of the space age from the 1960's
issued in 2012 it shows the clouds on Venus from a photo taken by the Venus Express probe. The European Space Agency's Venus Express spent eight years in orbit. Part of its mission was to study the atmosphere and ionosphere of Venus. These clouds may look benign, but by tracking the clouds in images, it was found that average wind speeds around this 'super-rotating' planet have increased from roughly 300km/h to 400km/h over a period of six Earth years.
Venus Express died in December 2014 after exhausting its propellant during a series of thruster burns to raise its orbit following the low altitude aerobraking during which it dipped lower into the atmosphere on its closest approach to the planet.
from the ESA website:
Normally, the spacecraft would perform routine thruster burns to ensure that it did not come too close to Venus and risk being lost in the atmosphere. But this unique adventure was aimed at achieving the opposite, namely reducing the altitude and allowing an exploration of previously uncharted regions of the atmosphere.
The campaign also provided important experience for future missions – aerobraking can be used to enter orbit around planets with atmospheres without having to carry quite so much propellant.