Happy leap day!!!
Once every four years, an extra calendar day is added: a leap day. But why?
The reason for adding leap days to the calendar is to align the calendar year with the actual year – which is defined by the time it takes Earth to circle the sun. It is equal to 365 days, 5 hours, 48 minutes and 46 seconds, or 365.24219 days.
If all calendar years contained exactly 365 days, they would drift from the actual year by about 1 day every 4 years. Eventually, July would occur during the northern hemisphere winter! Wouldn’t that be weird?
To correct (approximately), we add 1 day every 4 years…resulting in a leap year.
By making most years 365 days but every fourth year 366 days, the calendar year and the actual year remain more nearly in step.
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Earth isn’t the only planet in the solar system with spectacular light shows. Both Jupiter and Saturn have magnetic fields much stronger than Earth’s. Auroras also have been observed on the surfaces of Venus, Mars and even on moons (e.g. Io, Europa, and Ganymede). The auroras on Saturn are created when solar wind particles are channeled into the planet’s magnetic field toward its poles, where they interact with electrically charged gas (plasma) in the upper atmosphere and emit light. Aurora features on Saturn can also be caused by electromagnetic waves generated when its moons move through the plasma that fills the planet’s magnetosphere. The main source is the small moon Enceladus, which ejects water vapor from the geysers on its south pole, a portion of which is ionized. The interaction between Saturn’s magnetosphere and the solar wind generates bright oval aurorae around the planet’s poles observed in visible, infrared and ultraviolet light. The aurorae of Saturn are highly variable. Their location and brightness strongly depends on the solar wind pressure: the aurorae become brighter and move closer to the poles when the solar wind pressure increases.
Credit: ESA/Hubble (M. Kornmesser & L. Calçada)
Wonderfully smooth wagon-wheel effect from Saturn’s polar hexagon. Photographed by Cassini, 22 March 2014.
A stunning high res photo of Saturn’s Moon Enceladus
Solar Analemma for the year 2015 shot at Sulmona, Abruzzo, Italy.
js
Astronomy compels the soul to look upward, and leads us from this world to another
Plato (via back-to-the-stars-again)
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Planet Ring Set
Just a socially awkward college student with an interest in the celestial bodies in our universe.
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