Metric units of time larger than the second are most commonly seen only in a few scientific contexts such as observational astronomy and materials science, although this depends on the author.
This makes them problematic for use against a linear and regular time scale such as that defined by the SI, since it is not clear which version is being used.
Instead, the table uses the annum or astronomical Julian year (365.25 days of 86,400 seconds), denoted with the symbol a.
10–20 cs (=0.1–0.2 s): The human reflex response to visual stimuli In this table, large intervals of time surpassing one second are catalogued in order of the SI multiples of the second as well as their equivalent in common time units of minutes, hours, days, and Julian years.
86.399 ks (23 h 59 min 59 s): The length of one day with a removed leap second on UTC time scale.
86.401 ks (24 h 0 min 1 s): One day with an added leap second on UTC time scale.
31.55815 Ms (365 d 6 h 9 min 10 s): The length of the true year, the orbital period of the Earth 126.2326 Ms (1461 d 0 h 34 min 40 s): The elected term of the President of the United States or one Olympiad (1 Gs = over 31 years and 287 days = 1,000,000,000 s) 2.5 Gs: (79 a): The typical human life expectancy in the developed world 3.16 Gs: (100 a): One century 31.6 Gs: (1000 a, 1 ka): One millennium, also called a kilo-annum (ka) 63.8 Gs: The approximate time since the beginning of the Anno Domini era as of 2019 – 2,019 years, and traditionally the time since the birth of Jesus Christ 194.67 Gs: The approximate lifespan of time capsule Crypt of Civilization, 28 May 1940 – 28 May 8113 363 Gs: (11.5 ka): The time since the beginning of the Holocene epoch 814 Gs: (25.8 ka): The approximate time for the cycle of precession of the Earth's axis (1 Ts = over 31,600 years = 1,000,000,000,000 s) 31.6 Ts (1000 ka, 1 Ma): One mega-annum (Ma), or one million years 79 Ts (2.5 Ma): The approximate time since earliest hominids of genus Australopithecus 130 Ts (4 Ma): The typical lifetime of a biological species on Earth 137 Ts (4.32 Ma): The length of the mythic unit of mahayuga, the Great Age, in Hindu mythology.
7.9 Ps (250 Ma): The approximate time since the Permian-Triassic extinction event, the actually largest known mass extinction in Earth history which wiped out 95% of all extant species and believed to have been caused by the consequences of massive long-term volcanic eruptions in the area of the Siberian Traps.
16 Ps (510 Ma): The approximate time since the Cambrian explosion, a massive evolutionary diversification of life which led to the appearance of most existing multicellular organisms and the replacement of the previous Ediacaran biota.
At this point in time the stellar evolution of the Sun will have increased its luminosity to the point that enough energy will be reaching the Earth to cause the evaporation of the oceans and their loss into space (due to the UV flux from the Sun at the top of the atmosphere dissociating the molecules), making it impossible for any life to continue.
136 Ps (4.32 Ga): The length of the legendary unit Kalpa in Hindu mythology, or one day (but not including the following night) of the life of Brahma.
Under this scenario, dark energy increases in strength and power in a feedback loop that eventually results in the tearing apart of all matter down to subatomic scale due to the rapidly increasing negative pressure thereupon 300 – 600 Es (10 – 20 Ta): The estimated lifetime of low-mass stars (red dwarfs) 9.85 Zs (311 Ta): The entire lifetime of Brahma in Hindu mythology.
32 Rs (1×1021 a): Highest estimate of the time until all stars are ejected from galaxies or consumed by black holes.
1,340,009 Qs (4.134105×1028 years): The time period equivalent to the value of 13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.0.0.0.0 in the Mesoamerican Long Count, a date discovered on a stele at the Coba Maya site, believed by archaeologist Linda Schele to be the absolute value for the length of one cycle of the universe[17][18] 2.6×1011 Qs (8.2×1033 years): The smallest possible value for proton half-life consistent with experiment[19] 1023 Qs (3.2×1045 years): The largest possible value for the proton half-life, assuming that the Big Bang was inflationary and that the same process that made baryons predominate over antibaryons in the early Universe also makes protons decay[20] 6×1043 Qs (2×1066 years): The approximate lifespan of a black hole with the mass of the Sun[21] 4×1063 Qs (1.3×1086 years): The approximate lifespan of Sagittarius A*, if uncharged and non-rotating[21] 5.4×1083 Qs (1.7×10106 years): The approximate lifespan of a supermassive black hole with a mass of 20 trillion solar masses[21]
Qs: The scale of an estimated Poincaré recurrence time for the quantum state of a hypothetical box containing an isolated black hole of stellar mass[22] This time assumes a statistical model subject to Poincaré recurrence.
Qs: The scale of an estimated Poincaré recurrence time for the quantum state of a hypothetical box containing a black hole with the mass of the observable Universe.