Exa-
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Exa is a decimal unit prefix in the metric system denoting 1018 or 1000000000000000000. It was added as an SI prefix to the International System of Units (SI) in 1975,[1] and has the unit symbol E.
Exa comes from the Ancient Greek ἕξ, used as a prefix ἑξά-, meaning six (like hexa-), because it is equal to 10006.
Examples:
- The total storage needed by Google Mail as of April 2012, ignoring backups and compression, is more than an exabyte (10,240 megabytes of storage per user multiplied by an estimated 260 million users).
- 1 EeV = 1018 electronvolts = 0.1602 joule
- 1 exasecond is approximately 32 billion years
- 1 exametre is approximately 110 light years
- 0.43 Es ≈ the approximate age of the Universe
- 1.6 Em—172 ± 12.5 light years—Diameter of Omega Centauri (one of the largest known globular clusters, perhaps containing over a million stars)[2][3]
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- ^ Prefixes adopted before 1960 already existed before SI. 1873 was the introduction of the CGS system.
See also[edit]
References[edit]
- ^ "Resolution 10 of the 15th meeting of the CGPM (1975)". International Bureau of Weights and Measures. Retrieved 2012-04-18.
- ^ distance × sin( diameter_angle ), using distance of 5 kpc (15.8 ± 1.1 kly) and angle 36.3', = 172 ± 12.5 ly.
- ^ van de Ven, G.; van den Bosch, R. C. E.; Verolme, E. K.; de Zeeuw, P. T. (January II 2006). "The dynamical distance and intrinsic structure of the globular cluster ω Centauri". Astronomy and Astrophysics. 445 (2): 513–543. arXiv:astro-ph/0509228
. Bibcode:2006A&A...445..513V. doi:10.1051/0004-6361:20053061.
best-fit dynamical distance D=4.8±0.3 kpc ... consistent with the canonical value 5.0±0.2 kpc obtained by photometric methods
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- International Bureau of Weights and Measures (2006), The International System of Units (SI) (PDF) (8th ed.), ISBN 92-822-2213-6
External links[edit]
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