Britannica School: Comets
Britannica School: Edmond Halley
GALE Science: Great comets in history
GALE Science: Comets that changed the world
Out in Space: Comets
Time Machine (1909): The Arrival of Halley's Comet
Comet ISON time-lapse montage. These six images (moving left to right) show the comet from September to November 2013.
Comet ISON, time-lapse montage. Photograph. Britannica ImageQuest, Encyclopædia Britannica, 31 Aug 2017.
quest.eb.com/search/132_1472525/1/132_1472525/cite. Accessed 28 Sep 2020.
Comet passing near Earth, computer artwork.
Comet passing Earth. Photography. Britannica ImageQuest, Encyclopædia Britannica, 25 May 2016.
quest.eb.com/search/132_1297521/1/132_1297521/cite. Accessed 28 Sep 2020.
Optical image of comet Hale-Bopp as it passes through the constellation of Perseus, showing its gas and dust tails.
Optical image of comet Hale-Bopp in the night sky. Photography. Britannica ImageQuest, Encyclopædia Britannica, 25 May 2016.
quest.eb.com/search/132_1295358/1/132_1295358/cite. Accessed 28 Sep 2020.
Optical image showing the head (coma) and part of the tail of Comet Hyakutake, one of the brightest comets to appear in the sky.
Head & tail of comet Hyakutake. Photography. Britannica ImageQuest, Encyclopædia Britannica, 25 May 2016.
quest.eb.com/search/132_1294999/1/132_1294999/cite. Accessed 28 Sep 2020.
Comets, Stars, Planets by 
Killer Rocks from Outer Space by 
Diagram: First Comet to Hit Earth. ProQuest, Ann Arbor, 2013. SIRS Discoverer, https://explore.proquest.com/sirsdiscoverer/document/2257314238?accountid=147606.
Tunguska Comet. ProQuest, Ann Arbor, 2008. SIRS Discoverer, https://explore.proquest.com/sirsdiscoverer/document/2256524593?accountid=147606.