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The Sun

The Sun is a yellow dwarf star (G2V), about 4.6 billion years old, and the dominant gravitational force in the Solar System. It has a diameter of roughly 1.4 million kilometers and contains around 99.8% of the Solar System’s mass. Nuclear fusion in its core converts hydrogen into helium, producing energy that warms the planets. Above the core lie the radiative and convective zones, followed by the visible photosphere (~5,500 °C), the chromosphere, and the much hotter corona (~2 million °C).

Source: science.nasa.gov

APODs including "The Sun"

Chicagohenge: Equinox in an Aligned City

22/09/2024

Chicagohenge: Equinox in an Aligned City
Image Credit: Anthony Artese / NASA APOD

Chicago, in a way, is like a modern Stonehenge. The way is east to west, and the time is today. Today, and every equinox, the Sun will set exactly to the west, everywhere on Earth. Therefore, today in Chicago, the Sun will set directly down the long equatorially-aligned grid of streets and buildings, an event dubbed #chicagohenge. Featured here is a Chicago Henge picture taken during the equinox in mid-September of 2017 looking along part of Upper Wacker Drive. Many cities, though, have streets or other features that are well-aligned to Earth's spin axis. Therefore, quite possibly, your favorite street may also run east - west. Tonight at sunset, with a quick glance, you can actually find out.