Mya (unit)

Information about Mya (unit)

For other uses of "mya", see mya (disambiguation).

In astronomy, geology, and paleontology, mya or "m.y.a." is an abbreviation for million years ago. This abbreviation is commonly used as a unit of time to denote length of time before the present or "B.P." (before AD 1950). Specifically, one mya is equal to 10⁶ years ago. The popular term 'mya' is replaced in scientific literature with Ma (megaannum).

Like the related unit bya or "b.y.a.," ("billion years ago"), mya is traditionally written in lowercase. The common term bya is replaced in scientific literature with Ga (gigaannum).

Events around 1 mya:

Astronomical deep time:

The light we see now from the Andromeda Galaxy started 2.5 mya
The light we (do not) see now from the centre of the Milky Way started 0.026 mya

Geologic periods (Neogene):

Pliocene 5.3 to 1.8 mya
The last geomagnetic reversal was 0.78 mya
The (Eemian interglacial) Ice Age started 0.13 mya
Holocene started 0.01 mya

Prehistoric Paleontology:

Homo erectus existed from 1.8 to 0.07 mya
and learned to control fire from 1.5 to 0.5 mya
and colonized Asia from 0.5 to 0.3 mya
Homo sapiens separated from Neanderthal lineage 0.6 mya
and emerged out of Africa from 0.076 mya
and entered Australasia from 0.07 mya
and colonized all of Eurasia 0.04 mya
and formed cultures since the Upper Paleolithic Revolution 0.04 mya

units of measurement have played a crucial role in human endeavour from early ages up to this day. Disparate systems of measurement used to be very common. Now there is a global standard, the International System (SI) of units, the modern form of the metric system.
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time.

One view is that time is part of the fundamental structure of the universe, a dimension in which events occur in sequence, and time itself is something that can be measured.
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present is the time that is perceived directly, not as a recollection or a speculation. It is often considered as a point in space-time, often called now, but it may also be viewed as a duration (see specious present).
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Before Present (BP) years are a time scale used in archaeology, geology, and other scientific disciplines to specify when events in the past occurred. Because the "present" time changes, standard practice is to use 1950 as the arbitrary benchmark of what's considered "present".
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A year (from Old English gēr) is the time between two recurrences of an event related to the orbit of the Earth around the Sun. By extension, this can be applied to any planet: for example, a "Martian year" is the time in which Mars completes its own orbit.
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Annum is a Latin noun meaning year. It is the accusative singular of the second declension masculine noun annus (nominative), anni (genitive) [1] .

As a unit of time, it is defined as exactly 365.
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In astronomy, geology, and paleontology, bya or "b.y.a." is an acronym for billion years ago. This abbreviation is commonly used as a unit of time to denote length of time before the present. Specifically, one bya is equal to 10⁹ years ago.
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1,000,000,000 (alternately known as one thousand million and one billion, see below) is the natural number following 999,999,999 and preceding 1,000,000,001.

In scientific notation, it is written as 10⁹.
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For the minimalist musical sub-genre, see .

Lower case or lowercase or minuscule letters are the smaller form of letters, as opposed to capital letters: for example, the letter "a" is lower case while the letter "A"
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Andromeda Galaxy
A visible light image of the Andromeda Galaxy.
Credit: John Lanoue.
Observation data: J2000 epoch
Constellation: Andromeda
Right ascension: 00^h 42^m 44.
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Milky Way (a translation of the Latin Via Lactea, in turn derived from the Greek Γαλαξίας (Galaxias) sometimes referred to simply as "the Galaxy"), is a barred spiral galaxy that lies with the Local Group of galaxies
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Oceanic crust 0-20 Ma
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A geologic period is a subdivision of geologic time that divides an era into smaller timeframes. The equivalent term used to demarcate rock layers and the fossil record is the system; thus the rocks of the Devonian System were laid down during the Devonian Period.
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For the hawkmoth genus, see Neogene (moth).

Neogene Period is a unit of geologic time starting 23.03 ± 0.05 million years ago. The Neogene Period follows the Paleogene Period of the Cenozoic Era.
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The Pliocene epoch (spelled Pleiocene in some older texts) is the period in the geologic timescale that extends from 5.332 million to 1.806 million years before present.

The Pliocene is the second epoch of the Neogene period in the Cenozoic era.
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The Brunhes-Matuyama Reversal was a geologic event, approximately 780,000 years ago, when the Earth's magnetic field last underwent reversal. The reversal occurred over several thousand years.
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The Eemian interglacial era (known as the Sangamon interglacial in North America, the Ipswichian interglacial in the UK, and the Riss-Würm interglacial in the Alps) is the second-to-latest interglacial era of the Ice Age. It began about 131,000 years ago.
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ice age is a period of long-term reduction in the temperature of Earth's climate, resulting in an expansion of the continental ice sheets, polar ice sheets and mountain glaciers.
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The Holocene epoch is a geological period, which began approximately 11,550 calendar years BP (about 9600 BC) and continues to the present. The Holocene is part of the Neogene and Quaternary periods.
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Prehistory (Latin, præ = before Greek, ιστορία = history) is a term often used to describe the period before written history. Paul Tournal originally coined the term Pré-historique
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Palaeontology redirects here. For the scientific journal, see Palaeontology (journal).

Paleontology, palaeontology or palæontology (from Greek: paleo, "ancient"; ontos
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H. erectus

Binomial name
†Homo erectus
(Dubois, 1892)

Synonyms

† Pithecanthropus erectus
† Sinanthropus pekinensis
† Javanthropus soloensis
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Fire is an oxidation process that releases energy in varying intensities in the form of light (with wavelengths also outside the visual spectrum) and heat and often creates smoke. It is commonly used to describe either a fuel in a state of combustion (e.g.
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Asia is the world's largest and most populous continent. It covers 8.6% of the Earth's total surface area (or 29.4% of its land area) and, with almost 4 billion people, it contains more than 60% of the world's current human population.
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