Main content
Asaph Hall discovers Phobos and Deimos
The 19th and early 20th century American astronomer Asaph Hall discovered Mars' small moons, Phobos and Deimos. Observations of the moons' orbits allowed others to calculate the Red Planet's gravity, which is just under half that of Earth's.
Duration:
This clip is from
Featured in...
![]()
Astronomy Finder
Watch Solar System video clips from the 麻豆社 Archive.
More clips from The Red Planet
-
![]()
No stone left unturned
Duration: 03:29
-
![]()
Viking's instruments
Duration: 01:35
-
![]()
Mariner 9 finds new features
Duration: 03:03
-
![]()
Mariner 4 takes Mars photos
Duration: 01:49
More clips from Horizon
-
![]()
The results are in...—2021, Horizon Special: The Vaccine
Duration: 02:02
-
![]()
Pluto鈥檚 first pictures—2020, Pluto: Back from the Dead
Duration: 02:30
