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HD1 is one of the earliest and most distant known galaxies yet identified in the observable universe, having a spectroscopic redshift of z = 13.27, meaning that the light from the galaxy travelled for 13.5 billion years on its way to Earth, which due to the expansion of the universe, corresponds to a proper distance of approximately 33.4 billion light-years (10.2 billion parsecs).
In physical cosmology, the age of the universe is the time elapsed since the Big Bang: 13.8 billion years. [1] Astronomers have two different approaches to determine the age of the universe . One is based on a particle physics model of the early universe called Lambda-CDM , matched to measurements of the distant, and thus old features, like the ...
13.6–13.5 billion years (300-200 Mya): Sirius, the brightest star in the Earth's sky, forms. 13.7 billion years (100 Mya): Formation of Pleiades Star Cluster; 13.73 billion years (70 Mya): North Star, Polaris, one of the significant navigable stars, forms; 13.780 billion years (20 Mya): Possible formation of Orion Nebula
One galactic year is approximately 225 million Earth years. [2] The Solar System is traveling at an average speed of 230 km/s (828,000 km/h) or 143 mi/s (514,000 mph) within its trajectory around the Galactic Center, [ 3 ] a speed at which an object could circumnavigate the Earth's equator in 2 minutes and 54 seconds; that speed corresponds to ...
[1] [13] However, more recent models of its stellar evolution have suggested revision of the star's age to 13.7 billion years [14] or 12 billion years. [ 5 ] Dubbed the " Methuselah Star" by the popular press due to its age, [ 15 ] [ 16 ] the star must have formed soon after the Big Bang [ 1 ] and is one of the oldest stars known as of 2021. [ 5 ]
After 1.5 million years ago (extinction of Paranthropus), all fossils shown are human (genus Homo). After 11,500 years ago (11.5 ka, beginning of the Holocene), all fossils shown are Homo sapiens (anatomically modern humans), illustrating recent divergence in the formation of modern human sub-populations.
The Younger Dryas impact hypothesis (YDIH) proposes that the onset of the Younger Dryas (YD) cool period at the end of the Last Glacial Period, around 12,900 years ago was the result of some kind of cosmic event with specific details varying between publications. [1]: Sec 1 The hypothesis is widely rejected by relevant experts.
About 1.3 million years ago the object may have passed within a distance of 0.16 parsecs (0.52 light-years) to the nearby star TYC 4742-1027-1, but its velocity is too high to have originated from that star system, and it probably just passed through the system's Oort cloud at a relative speed of about 15 km/s (34,000 mph; 54,000 km/h).