I am really thrilled that my native Germany and the country that I'm living in, the USA, issued stamps last fall which depict astronomical images, thus combining my two favorite hobbies.  The U.S. had issued lots of space stamps before, for the moon landing of course, about their space program in general and several sets of space fantasy.  I don't like the latter ones because why fiction if the real science is even better!

At the Hubble web page people were invited to put in their support and the original proposal called for twenty stamps, as has been possible for lots of more trivial issues in the past years, such as "dolls" and "comic strips".  So since the U.S. Postal Service issued only five Hubble stamps (better be happy, anyway!), I attached my favorites in the same format; but of course those aren't stamps.  I wish.  They will also issue a huge sheet on space exploration in July.

The images provide links to the respective postal administrations and to the Hubble images site.

The German stamps, "Für die Wohlfahrtspflege 1999: Kosmos"
Issued by Deutsche Post AG
Design: Benjamin Blase, Kassel
First Day, Bonn, October 14, 1999

These stamps can be purchased at face value (but $20 shipping charge) through Unicover in Cheyenne, WY.

The top stamp shows our closest galactic neighbor, the Andromeda galaxy.  The inset shows the same in the radio part of the spectrum.
If you purchase a starfinder (about $2-5), then go into the country side on a dark moonless night, you can find the Andromeda galaxy (also called a "nebula" or M31) relatively easy with the naked eye and/or binoculars.

The next stamp depicts a historical, fanciful star map of the constellation Cygnus, the Swan, from a 1782 atlas.  The inset shows the same region again in radio waves.
Cygnus' brightest star is one of three making up the summer triangle.  You can find Cygnus easily if you look for a big cross.  On a dark night you'll see the Milky Way running through it.  And with binoculars you are able to enjoy the myriad of stars in that part of the Milky Way which is the most crowded place besides the the Milky Way part that you find in Sagittarius.

The third stamp represents the Vela supernova remnant.  Both the large picture and the inset seem to show the Vela nebula in x-rays taken by ESA's ROSAT satellite.  The blue part depicts a super hot gas bubble of several million degrees Kelvin.
Vela is a constellation in the southern hemisphere.  The remnant itself can be seen in large amateur telescopes (about 8 inch aperture) with a low power eyepiece and an Oxygen III filter.

The fourth stamp portrays one of the most exciting and important astronomical events of the 20th century.  This infrared picture shows two impacts of the fragmented comet Shoemaker-Levy 9 as these fragments plunged into Jupiter's atmosphere over the course of a week in July 1994.  The inset is unique since it is a hologram which shows a fragment moving towards Jupiter on the right and the impact on the left, when you tilt and move the real stamp in front of you.
Jupiter is the brightest point source in the sky next to Venus.  Everybody has seen it - although without knowing it.  You find its current position on the back of your starfinder.  Through binoculars you can see its four large moons which look like "stars".  Make sure to hold your binoculars very steady, e.g. put your elbows on your car roof.  With a moderate aperture telescope on can also see the cloud bands.

The last stamp represents the entire sky in g-radiation (g=gamma).  On the bottom you see NASA's Compton g-ray observatory which captured this image.  The inset is another hologram.
As mentioned before, the Milky Way stretches as a faint band from one horizon to the other.  Great for binoculars.

The United States stamps, "Space Achievement and Exploration"
Issued by the U.S. Postal Service
Design:
First Day, July 2000

"These stamp designs will educate the world about the accomplishments, wonder and excitement of the American space program.  They display the achievements of our space program, as well as the infinite possibilities of future space endeavor: Escaping the Gravity of Earth, Landing on the Moon, Exploring the Solar System and Probing the Vastness of Space.
The press sheet poster will contain four panes, plus a central stamp panel. The lower right quadrant features a Priority Mail rate stamp representing American technology solving the problems of escaping the gravitational pull of Earth and learning how to send missions into Earth's orbit. The upper left quadrant moves a notch farther into space, commemorating on an Express Mail rate stamp the Apollo program that culminated in landing American astronauts on the moon. The background image is from the Apollo 16 mission.
Moving farther from Earth, the lower left quadrant represents the exploration of our solar system. These five $1 stamps will be the first pentagonal stamps ever issued by the Postal Service. The upper right quadrant addresses the exploration of deep space. These six stamps will be issued in international rate denominations. The $11.75 stamp in the central panel will be the first circular hologram stamp ever issued by the Postal Service. It features a view of Earth from the Apollo 17 spacecraft and shows the continents of Africa and Antarctica."

I will comment on these once I've seen larger images.
 

The United States stamps, "Space Achievement and Exploration"
Issued by the U.S. Postal Service
Design:
First Day, April 10, 2000

From the U.S. Postal Service: Edwin Powell Hubble
"This stamp pane pays tribute to the work and contributions of Edwin Powell Hubble and the Hubble Space Telescope, which was named in his honor. Hubble was an eminent American astronomer whose work furthered our understanding of the universe. He was instrumental in the building of Palomar Observatory in California and conducted research there when it was completed.
Born Nov. 20, 1889, in Marshfield, Mo., Hubble determined that galaxies exist outside of and are receding from our own galaxy, the Milky Way. His observations demonstrated that the universe is expanding. Hubble died Sept. 28, 1953, in San Marino, Calif.
The Hubble Space Telescope (HST), launched in April 1990, orbits the Earth and sends images of astronomical objects back to scientists. The HST can see farther into the universe than Earth-based observation tools and provides astronomers with stunningly clear images.
The five stamp images - Eagle Nebula, Ring Nebula, Lagoon Nebula, Egg Nebula and Galaxy NGC 1316 - were captured by the HST. The images are visual representations of data taken by the HST that have been processed, and in some cases colorized, for scientific purposes.
A 1949 black-and-white photograph of Hubble, posing with the 48-inch Schmidt Telescope at Palomar Observatory, serves as the selvage image."
 

The first stamp, showing the Eagle nebula, is a part of the original picture.  Because of its extraordinary beauty, the Eagle nebula (also M16) in Aquarius became the flagship of Hubble images.  It is a stellar nursery.  A few very hot violet stars are already born while protostars of lower mass are still cocooned in "little fingers" a few light-years wide.
You can see it with an 8 inch telescope.

The Ring nebula or M57 in Lyra is the gently pushed off atmosphere of a formerly dying red giant whose core is now a dead white dwarf.
The Ring nebula is my favorite object when using WNCC's 8 inch Schmidt-Cassegrain with a high power eyepiece.  It appears as a "smoke ring".

The Lagoon nebula or M8 in Sagittarius is another stellar nursery.
It too is one of my favorite objects, also for binoculars, since it is easy to find and looks quite pretty.  It lies in a beautiful part of the Milky Way.

The Egg nebula is like the Ring a planetary nebula with a white dwarf as its stellar remnant.

"A preliminary inspection indicates that [the galaxy] NGC 1316 is an enormous elliptical galaxy that started devouring a smaller spiral galaxy neighbor about 100 million years ago."

These are the Hubble images I would have chosen:

From upper left, clockwise: Saturn in UV, showing its Southern Lights; the Butterfly, another planetary nebula - my most favorite among my Hubble favorites; a Gravitational Lens, the light of a distant object, a quasar is deflected by the galaxy group in the center, producing several arc images of that same quasar; the Hourglass nebula, again a planetary; the Eagle, one of my cherished images, too; Eta Carinae, a star with 100 solar masses, erupting irregularly; the heart of the Orion nebula, the four stars are visible in an 8 inch with high power, but the proplyds (protoplanetary disks) are Hubble's discovery; the Cateye, I bet it's no coincidence that planetary nebulae produce many of the prettiest images; the Antennae, two colliding galaxies in the process of merging, setting off "brilliant bursts of star birth"; Centaurus A, a near by galaxy showing star birth and a massive black hole at its center; the Supernova 1987A remnant, the expanding shell of the brightest Supernova this century.

You can vote on your three most favorite Hubble pictures on this survey.

* Two-hundred years ago Charles Messier, a French comet hunter, collected a list of 110 fuzzy objects that look like comets but are not.  His legacy is this great list of M objects comprising galaxies, planetary nebulae, globular and open clusters, supernova remnants and a few normal star fields.

Space related stamps issued by these postal agencies.

United States:
Space Exploration:  1960 Echo I ;  62 Project Mercury ;  64 Robert H. Goddard, Airmail stamp ;  67 Accomplishments in Space, 2 stamps ;  69 Apollo 8 ;  69 Moon Landing, Airmail stamp ;  71 Space Achievement Decade, 2 stamps ;  75 Apollo - Soyuz Docking, 2 stamps ;  78 Viking missions to Mars ;  81 Space Achievement (explorations to the planets), block of 8 stamps ;  89 Moon Landing, 20th Anniversary ;  91 Space Exploration, block of 10 stamps ;  92 Space Adventures, block of 4 stamps ;  92 Theodore von Kármán ;  94 Moon Landing, 25th Anniversary, 2 stamps;  95 Space Shuttle, Airmail stamp ; 96 Space Shuttle, Airmail stamp ; 97 Mars Pathfinder, block ;  98 Space Shuttle, Airmail stamp ;  99 First Satellite in Space ;  99 Moon Landing ;  99 Pioneer at Jupiter ;  2000 Space Achievement and Exploration, block of 15 stamps ;
Space Fantasy:  1989 Future Mail Transportation, block of 4 Airmail stamps ;  89-95 Future Space Station, Envelope with hologram stamp ;  91 Space Vehicle ;  93 Space Fantasy, block of 5 stamps ;  98 Space Discovery, block of 5 stamps ;
Astronomy:  1981 Space Achievement (explorations to the planets), block of 8 stamps ; 85 Halley's Comet, Aerogramme ; 2000 Hubble images, block of 5 stamps ;

Germany (includes West Germany):
Space Exploration:  1975 News Satellite ;  75 Space Shuttle ;  76 Radio Telescope ;  86 European Satellite Technology ;  91 European Space Exploration, 2 stamps  ;  99 Cosmos, set of 5 stamps  ;
Astronomy:  1973 Nicholas Copernicus ;  84 Friedrich Wilhelm Bessel ;  86 Halley's Comet, GIOTTO mission ;  87 Joseph von Fraunhofer ;  93 Sir Isaac Newton ;  99 Cosmos, set of 5 stamps  ;

East Germany:
Space Exploration:  1957 Sputnik ;  59 Rocket Landing on the Moon ;  61 First Manned Space Flight ;  61 Visit by Cosmonaut Titow to the GDR, set of 6 stamps ;  62 Spaceships Wostok 3 & 4, block ;  62 Five Years of Soviet Space Exploration, block of 8 stamps ;  63 Spaceships Wostok 5 & 6, 2 stamps ;  63 Visit by Cosmonauts Valentina Tereschkowa and Juri Gagarin to the GDR, 4 stamps ;  65 Woschod 2, 2 stamps  ;  68 Space Achievements, 2 stamps ;  71 Ten Years of Manned Soviet Space Flights, block of 8 stamps ;  71 Lunochod 1 ;  72 Weather Satellite Meteor, block ;  73 Days of Soviet Science ;  75 Sojus-Apollo Docking, set of 3 stamps ;  78 Inter-CosmosPprogram, set of 3 stamps and block ;  78 Joint Space Venture USSR-GDR;  78 Joint Space Venture USSR-GDR, set of 4 stamps and block ;  86 Twenty Five Years of Manned Soviet Space Flights, block of 4 stamps ;  88 Tenth Anniversary of Joint Space Venture USSR-GDR, set of 3 stamps ;  88 Tenth Anniversary of Joint Space Venture USSR-GDR, set of 3 stamps ;  89? Conference on Astronautics, set of 4 stamps .
Astronomy:  1964 International Year of the Quiet Sun, 3 blocks ;  67 Two Meter Reflector ;  71 Johannes Kepler ;  71 Zeiss Planetarium ;  72 Earth and Sky Globes, set of 6 stamps ;  73 Nicholas Copernicus ;  88 B. Brecht, Galileo at Telescope, block.