Universe And Science

2021-07-03 05:19:10 Apollo 15 Earthrise

Mosaic of a crescent Earth rising over the lunar horizon. This image was taken on August 3, 1971 by members of the Apollo 15 mission.

NASA/Al Worden/Justin Cowart ओपन / कमेंट

2021-07-01 15:50:05 ओपन / कमेंट

2021-07-01 04:49:48 Did You Know?

Halley's Comet, appearing about every 76 years, is arguably the most famous comet. It is the only naked-eye comet that can appear twice in a human lifetime.

The comet's perihelion (nearest point to the sun) is 0.5 AU at a velocity of 55 km/sec; its aphelion (farthest point to the sun) is 35 AU at a velocity of 1 km/sec. Hence, it has an orbital eccentricity of 0.967.

It is one of the darkest, or least reflective, objects in the solar system. It has an albedo of 0.03, which means that it reflects only 3% of the light that falls on it.

The last time it was here was in 1986, and it is projected to return in 2061. ओपन / कमेंट

2021-06-29 13:18:37 Albedo

Albedo is a non-dimensional, unitless quantity that indicates how well a surface reflects solar energy. It commonly refers to the whiteness of a surface. Albedo varies between 0 and 1. A value of 0 means the surface is a perfect absorber that absorbs all incoming energy. A value of 1 means the surface is a perfect reflector that reflects all incoming energy. It is commonly used in astronomy to describe the reflective properties of planets, satellites, and asteroids.

Enceladus, a moon of Saturn, has one of the highest known albedos of any body in the Solar System, with an albedo of 0.99. Another notable high-albedo body is Eris, with an albedo of 0.96. ओपन / कमेंट

2021-06-29 04:34:45 The first ever film to feature a total solar eclipse.

Filmed on May 28, 1900 in North Carolina (USA) by British magician Neville Maskelyne. Neville also successfully captured an eclipse two years earlier (i.e. on 1898) in India, but his tape was stolen.

Know More ओपन / कमेंट

2021-06-28 04:19:47 Saturn's rings are so thin that stars and planets can occasionally be seen through them, like automobile headlights penetrating a snowstorm. And what's interesting about the above image is that you can see Venus appears as a bright dot shining through Saturn's rings. This image was taken on Nov. 10, 2012, by NASA's Cassini spacecraft.

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2021-06-27 05:43:15 Cassini Image of Sunlight reflection off Jingpo Lacus (a hydrocarbon lake in the north polar region of Titan), And did you know? Titan (Saturn's largest moon) is the only celestial object besides Earth known to host stable bodies of liquid on its surface.

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2021-06-25 05:49:14 Storms in Jupiter's Northern Hemisphere.

NASA/JPL-Caltech/SwRI/MSSS ओपन / कमेंट

2021-06-24 08:08:22 The first image of the Earth from space (1946) compared to today. ओपन / कमेंट

2021-06-23 04:26:00 This is how the view of the Earth from the Sun's side changes throughout the year.

Time-lapse compiled from DSCOVR satellite images. All images were taken at the same time (11:01), but on different days. ओपन / कमेंट