Speed of light they appeared 13 billion years ago, when the universe was less than a billion years old. The fact that more distant objects appear to be younger, due to the finite speed of light, allows astronomers to infer the evolution of stars, of galaxies, and of the universe itself. Astronomical distances are sometimes expressed in light-years, especially in popular science publications and media. A light-year is the distance light travels in one year, around 9461 billion kilometres, 5879 billion miles, or 0.3066 parsecs. In round figures, a light year is nearly 10 trillion kilometres or nearly 6 trillion miles. Proxima Centauri,
2-in-1 PC both tablets and laptops. The later 2-in-1 PCs comprise a category that is a sibling to both the pre-2-in-1 convertibles and hybrids. Models of 2-in-1 PC were each similarly denominated either a "2-in-1 convertible" or "2-in-1 detachable", respectively, and despite borrowing the terminology of the pre-2-in-1 PCs, the two species of 2-in-1 PCs are distinct from the two species of pre-2-in-1 PCs because 2-in-1 PCs have additional features of traditional laptops. 2-in-1 PCs consist of portable computer components within light and thin chassis, and exemplify technological convergence. They are convenient for media consumption and non-intensive tasks in tablet mode yet