Tunguska event - the largest impact event on Earth in recorded history. Studies have yielded different estimates of the superbolide's size, on the order of 60 to 190 metres (200 to 620 feet), depending on whether the body was a comet or a denser asteroid. Modern calculations that include the effect of the object's momentum estimate that the airburst had an energy range from 3 to 5 megatons of TNT.
The first recorded expedition was conducted in 1927 by Leonid Kulik team following another three and an aerial survey. A stamp was issued in 1958 to commemorate the 50th anniversary of the event and Kulik efforts to explore it.
Sikhote-Alin event - an iron meteorite that disintegrated in Earth atmosphere and fell as a rain of debris on Feb 12, 1947 in Sikhote-Alin mountains (Far East Russia close to the Russian-Chinese border) near the remote village of Beitsukhe. The overall size of the debris was estimated at 70 tons with the largest weighting 1745 kilograms. After the conflict with China in 1969 Beitsukhe was renamed to Meteoritny.
A lot of people witnessed the event and between them was an artist Petr Medvedev who was in the middle of sketching the local landscape. His painting appeared on the stamp and cover commemorating 10th anniversary of the event in 1957.
Chelyabinsk meteorite event was the biggest since Tunguska in 1908. On the morning of Feb 15, 2013 a small asteroid (around 17 meters in diameter) entered Earth atmosphere, disintegrated and exploded at around 20km above Chelyabinsk area in Russia. The explosion yield was calculated as equivalent to 200 kiloton of TNT (although some sources estimate it as 500kT). Huge amount of small debris fell over the Etkulsk district while the biggest piece (over 500 kilograms) got into the Chebarkul Lake and was extracted half a year later.
This event was highly publicized. It was the most pictured astronomical event ever, YouTube videos accounted for over 100 million views in just 3 days. Several dozens of 2014 Sochi Winter Olympics gold medals got a piece of the meteorite welded inside – 10 of them were awarded on the 1st anniversary of the event Feb 15, 2014. Many people earned from selling meteorite pieces to collectors around the world.
A special postmark was used to celebrate 3rd anniversary of the event. One enthusiastic postcard designer and astrophilatelist from Chelyabinsk created a series of cards to commemorate the event and that is what I have along with some other private designs.
1958 International Geophysical Year Assembly special postmarks
6 month since the event Chelyabinsk State Pedagogical University postmark
2014 Sochi Winter Olympics gold medals with pieces of meteorite. Sochi Winter Olympics postmark - Feb 15, 2014
Chelyabinsk museum of local lore - place of meteorite debris storage 80th anniversary of Chelyabinsk State Pedagogical University postmark
meteorite explosion postcard
170th anniversary of Russian Geographical Society First Day of Issue postmarks - Jul 23, 2015
2nd anniversary of the event map of the meteorite fall Chelyabinsk State Pedagogical University postmark
2nd anniversary of the event Pedagogical University postmark
the tent on the ice of Chelarkul Lake
the beacon in the waters of Chebarkul Lake over the place of meteorite main fragment
3rd anniversary special postmark
the project of Chebarkul Lake analysis - before and after the event 3rd anniversary special postmark
2nd and 3rd anniversaries
Chelyabinsk event oil painting 3rd anniversary special postmark
nicely designed postcard with 3rd anniversary special postmark and personal inscription
3rd anniversary special postmark
old-style postcard with the picture of a hole in the ice of Chebarkul Lake where the main fragment landed
another nice private design with 3rd anniversary special postmark
Suomi NPP satellite gathered valuable data on Chelyabinsk meteorite event