NASA Time-Lapse Video From Space: Sunlit Earth Over One Year

Location of the DSCOVR satellite, in relation to the Earth and Sun, known as
Lagrange Point 1 (L1).
(Graphic Source: National Oceanic and Atmospheric Administration)

By Glenn A. Walsh

Reporting for SpaceWatchtower

On YouTube, NASA has released a time-lapse video (2 minutes, 46 seconds in length), taken from a distance of one million miles from the Earth, showing the Earth over a period of one year. More than 3,000 color photographs, taken at least once every two hours beginning on 2015 July 6, show several events (including a Solar Eclipse and Lunar Transits) that occurred on the sunlit side of our planet while rotating on its axis 366 times.

These photographs were taken by the EPIC (Earth Polychromatic Imaging Camera) camera on the DSCOVR (Deep Space Climate Observatory) satellite, sponsored by the National Oceanic and Atmospheric Administration (NOAA). This satellite is in orbit of the Earth, about a million miles away from our planet, at the spot in space known as Lagrange Point 1.

Lagrange Point 1 (L1) is one of five Lagrange Points in relation to three bodies in space. In this case, L1 is the point in space where the gravity of the Earth, gravity of the Sun, and, also, the Apparent Centrifugal Force of a third body (DSCOVR satellite) are in a rough equilibrium This allows the satellite, located in such a position, to remain in orbit around the Earth using a minimum of fuel, and to always remain directly between the Sun and the Earth.

The five Lagrange Points are named for 18^th century mathematician Joseph-Louis Lagrange, who wrote about these points in a 1772 paper regarding, what he called, the “three-body problem.”

EPIC takes images of ten different wavelengths. Then, three of these wavelengths, correlated to the colors red, green, and blue, are combined to provide a realistic, color image of what the viewer would see, if the viewer was on the satellite.

This video shows moving cloud and weather patterns and large storms, along with continents and oceans quickly passing along on the surface as each day passes. Good views of the North Pole and the South Pole are seen in the video, during their respective Summer seasons (when the respective Pole is tilted towards the Sun, and hence, also tilted towards the satellite).

The EPIC camera caught the Moon's shadow move across the Earth's surface during the 2016 March 8 - 9  Total Solar Eclipse, which was visible from parts of Indonesia and the Pacific Ocean. Additionally, since this satellite is four times farther from the Earth than is Earth's Moon, the EPIC camera viewed the Moon transit, or move across the Earth's disk, a couple of times during this year of observation (2015 July 16 and 2016 July 4).

As this satellite is “parked” at L1, it could view both the Sun and the sunlit Earth 24 hours a day. The DSCOVR satellite, operated by NOAA, is an Earth observation satellite which could help weather forecasting for NOAA's National Weather Service (NWS). Another satellite located at L1, SOHO (Solar and Heliospheric Observatory), continually watches and studies the Sun.

As an Earth observation satellite, DSCOVR and the EPIC camera are tasked with watching Earth's weather patterns, as well as measuring ozone and aerosol in the atmosphere, the type and height of clouds, vegetation on Earth's land masses, hotspots on the planet, and making estimates of Ultraviolet (UV) radiation on the Earth's surface. This is the first time we are receiving continual images of our planet from this great a distance. The DSCOVR satellite is expected to last at least five years.

NASA Time-Lapse Video: Link >>> https://www.youtube.com/watch?v=CFrP6QfbC2g

Internet Links to Additional Information ---

More on the DSCOVR satellite:
Link >>> https://en.wikipedia.org/wiki/Deep_Space_Climate_Observatory

More on the EPIC camera:
Link >>> https://en.wikipedia.org/wiki/Deep_Space_Climate_Observatory#EPIC

More on Lagrange Points:
Link 1 >>> http://www.haydenplanetarium.org/tyson/read/2002/04/01/the-five-points-of-lagrange
Link 2 >>> https://en.wikipedia.org/wiki/Lagrangian_point

More on Apparent Centrifugal Force and Centripetal Force:
Link 1 >>> http://phun.physics.virginia.edu/topics/centrifugal.html
Link 2 >>> http://sydney1206.blogspot.com/2013/05/centripetal-force.html
Link 3 >>> http://www.livescience.com/52488-centrifugal-centripetal-forces.html

More on NOAA:
Link >>> https://en.wikipedia.org/wiki/National_Oceanic_and_Atmospheric_Administration

Source: Glenn A. Walsh Reporting for SpaceWatchtower, a project of Friends of the Zeiss.

             2016 July 25.


                                                              
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Glenn A. Walsh, Project Director,
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