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A Brief History of High-Energy Astronomy: Pre-0 Common
Era (CE)
In Reverse Chronological Order
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|---|
| Apr, 4 BCE (or BC) |
Chinese astronomers observe and record for about a month a
`po star' towards the direction of the modern constellation of Aquila.
Wang et al. (ApJ, 569, L43, 2002) argue that this `po star', unlike most
others which are now believed to be comets, was actually a hypernova
(an exceptional supernova like SN 1998bw which has much more kinetic energy
release than the typical value), and that the soft gamma repeater SGR
1900+14 is the neutron star created in this event. |
| 48 BCE (or BC) |
Chinese astronomers observe and record a `guest star' which is now
suspected to be a supernova explosion, possibly the one which produced
the supernova remnant SNR 021.5-00.9 (Wang et al. 1986, Highlights of
Astronomy, 7, 583). |
| 134 BCE (or BC) |
Chinese (and Greek) astronomers observe and record a `guest star' which is
now suspected to be a supernova explosion, possibly the one which
produced the supernova remnant RCW 103 = SNR 332.4-00.4 (Wang et al.
1986, Highlights of Astronomy, 7, 583). |
| 240 BCE (or BC) |
The first reliably recorded appearance of Halley's Comet
(P1/Halley), by Chinese astronomers. |
| 523 BCE (or BC) |
Chinese astronomers observe and record a `guest star' which is now
suspected to be a supernova explosion, possibly the one which produced
the supernova remnant CTB 87 = SNR 074.9+01.2 (Wang et al. 1986,
Highlights of Astronomy, 7, 583). |
| 14th Century BCE (or BC) |
A great new star is observed by Chinese astronomers during the Shang
Dynasty and recorded on an "oracle bone of tortoise".
Xu et al. (1992, A&A, 256, 483) suggest that this event "may be the
first [supernova] explosion recorded by mankind" and was caused by the
explosion of a massive star in the nearby Rho Oph molecular cloud, and that
the effects are still visible as the gamma-ray source 2CG 353+16. |
| 5 thousand years ago |
The beginning of construction of the first phase of Stonehenge
(near the modern-day town of Amesbury in England). This complex of stones,
pits and ditches has many alignments which, it has been argued, suggest that
it was designed to be an astronomical observatory. |
| 7 thousand years ago |
Construction of a circular walled
compound near the modern-day town of Goseck in
Germany which has been claimed to be Europe's oldest astronomical
observatory, predating Stonehenge by more than 2000 years, based
on features that align with winter solstice sunrise and sunset. |
| 11 thousand years ago |
Beginning of the current interglacial period (the Holocene era)
on the Earth, following the end of the last Ice Age. |
| 3 million years ago |
A supernova explosion may have occurred nearby (10-100 parsecs), as
inferred from the discovery in deep-ocean layers of the unstable
isotope 60Fe which is created in significant amounts only in
supernovae. Other evidence for a nearby supernova several million years go
is the existence of the `Local Hot Bubble' in the interstellar
medium in which the Solar System is embedded (see
Fields et al. 2005 (ApJ, 621, 901) for more details on the 60Fe
measurements; but also see Fitoussi
et al. (2007, astro-ph preprint) for a follow-up study which fails to find
60Fe in the layers of a marine sediment deposited at this era).
|
| 65 million years ago |
The Cretaceous-Triassic (K-T) extinction event causes the
extinction of about 50 - 70% of the species of life on the Earth, most notoriously
the dinosaurs. This extinction event is widely
believed to be due to the impact of a large object such as
a comet or asteroid, and the
180 kilometer-diameter Chicxulub crater in
Mexico's Yucatan Peninsula is generally regarded to be the impact site.
For more on the origins and travails of
terrestrial life (and on the search for extraterrestrial life), see NASA's Astrobiology site. |
| 0.20 billion years ago |
The Triassic-Jurassic extinction event causes the
extinction of a good fraction of the species of life on the Earth, e.g., 20%
of marine species, amd many types of archosaurs, therapsids, and large
amphibians, perhaps due to the impact of a large object such as
a comet or asteroid (a
large crater in Manicouagan, Canada has been suggested as
the impact site). |
| 0.25 billion years ago |
The Permian-Triassic extinction event, also known as the `Great Dying'
causes the extinction of many species of life on the Earth, e.g., 95% of
marine species and 70% of land species, perhaps due to the impact of a large
object such as a comet or asteroid. This is the largest such extinction
event known in the history of life on earth. Recently, a 125-mile diameter
impact crater has been discovered off the coast of Australia, the Bedout Structure,
which appears to be the correct age and size for such an impact
event (see
Becker et al. 2004, Science, 304, 1469 for more details).
|
| 0.36 billion years ago |
The transition from the Devonian to the Carboniferous periods
causes the elimination of many species (about 70%) of life on the Earth.
This was not a sudden occurrence but occurred over a few million years, and thus
it is unlikely to have been caused by a large impact event.
|
| 0.44 billion years ago |
Two Ordovician-Silurian extinction events cause the
extinction of many species of life on the Earth, perhaps due to the onset and
decline of a major glaciation episode. |
| 0.50 billion years ago |
The Cambrian-Ordovician series of extinction events cause the
extinction of many species of life on the Earth, such as brachiopods, conodonts,
and trilobites.
Melott et al. (2004, International Journal of Astrobiology,
3, 55) have presented arguments that this extinction may have been
triggered by a gamma-ray burst associated with a nearby (within 3
kiloparsecs) galactic supernova. |
| 1.7 billion years ago |
The operation of the first-known nuclear reactors on the Earth in
natural uranium deposits in Oklo,
Gabon (West Africa). |
| 2 billion years ago |
The appearance on the Earth of eukaryotes, lifeforms with complex
cells in which the genetic material is contained in distinct nuclei.
|
| 3.5 billion years ago |
The beginning of life on the Earth, based on the age of the oldest
known terrestrial lifeforms. This is obtained from the geological
dating of fossilized bacteria, and is uncertain by +/- 0.5 billion years.
For more on the origins of terrestrial life and on the search for
extraterrestrial life, see NASA's Astrobiology site. |
| 3.8 billion years ago |
The end of the period of Late Heavy Bombardment of the surface of the
Earth (and of the Moon) by asteroids and comets. Many (but not all) scientists
in this field believe that prior, to this time, the Earth' surface was not a
viable site for the sustained development of life. |
| 4.557 billion years ago |
Formation of the Earth (strictly speaking, the era by which the
Earth had accumulated 64% of its present mass): accretion continued for
about another 20 million years, at which time the Earth was impacted by
a Mars-sized object (which has been dubbed Theia),
and the Moon formed out of the ejecta. |
| 4.567 billion years ago |
Formation of the Solar System (strictly speaking, the era
in which the oldest known accreted objects formed in the solar `nebula'):
see Jacobsen (2003, Science, 300, 1513) for a brief discussion of the era of
the formation of the Solar System and the Earth. |
| 8 billion years ago |
Formation of the first stars in the disk of our Galaxy, the Milky
Way, as inferred from measurements of the coolest and dimmest white
dwarf stars in the solar neighborhood, see e.g.,
Leggett et al., 1998, ApJ, 497, 294. |
| 11-12 billion years ago |
Formation of the first (oldest) stars in our Galaxy, the Milky Way,
as determined from the ages of stars in the oldest globular clusters, see e.g.,
D'Antona et al. 1997, ApJ, 477, 519. |
| 13.7 billion years ago |
Formation of the Universe, also known as the `Big Bang',
according to measurements of NASA's
Wilkinson Microwave Anisotropy Probe (WMAP). |
Acknowledgements
We would like to thank the following individuals for their
contributions to this page:
Jesse S. Allen, and
Ian M. George
along with
JPL's Space Calendar and the
Working Group for the History of Astronomy's
Astronomiae Historia (History of Astronomy) information pages.
Web page author: Stephen A. Drake (based on an original by Jesse S. Allen)
Web page maintainer: Stephen A. Drake
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