Category Archives: Astronomy

If Andromeda Galaxy were brighter, this is what we’d see

Andromeda Galaxy is the farthest object in the sky that we can see with the naked eye. But if you don’t know where to look, you won’t notice it. But if it were much brighter, its appearance in the sky would be sensational. The moon is a good reference about what we’d see in the image below:

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The Size Of Earth Compared to Other Planets and Stars (and the Universe)

When it comes to big numbers, very big numbers, the human brain is weak. In fact, our brains cannot deal with the really large numbers. That’s why when the subject is Earth, planets, Solar System, galaxies, and in general, the Universe, we cannot truly conceptualize the things. A lot of people think we’re “conquering” space (we are far, far away from that – and maybe we never will), or the “aliens” are regularly visiting Earth as if it is just an hour’s drive from there. In fact, these people don’t truly understand what are they talking about, how big is the universe, how far the stars are, and how the Earth is a tiny, tiny spot in a vast space we are still striving to understand.

But we can try to understand and conceptualize. To put things into a perspective, YouTube user morn1415 prepared a video (he updated a previous video with the new findings in the astronomy).

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How Eratosthenes calculated the Earth’s circumference

In 240 BC, the Greek astronomer, geographer, mathematician, music theorist and librarian Eratosthenes of Cyrene (c. 276 BC – c. 195/194 BC) calculated the circumference of the Earth without even leaving Egypt. Here’s how:

Eratosthenes knew that at local noon on the summer solstice (at the time of the longest day, about 21 June in the northern hemisphere) in Syene (modern Aswan, Egypt), the Sun was directly overhead – Syene was in fact slightly north of the tropic, though (1). Local noon is – technically when the sub-solar point is somewhere over your meridian, it’s noon for you. So, on that day, Syene is the sub-solar point of Earth (the sub-solar point on a planet is where its sun is perceived to be directly overhead). To learn more about the local noon and the subsolar point, see the article titled “How Earth Moves“.

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How Mars would look if it still had water

What if Mars still had liquid water on its surface and a thick atmosphere filled with clouds, like Earth? How would it look like? Software engineer Kevin Gill of JPL (NASA’s Jet Propulsion Laboratory) wondered this and prepared an image using data from NASA’s Mars Reconnaissance Orbiter (MRO)(1) and Mars Orbiter Laser Altimeter (MOLA)(2). The result is stunning!

Gill picked an arbitrary sea level and used GIMP (a free and open-source raster graphics editor used for image retouching and editing) to paint the features onto the satellite images using these measurements.

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Proxima Centauri b May Have Oceans

Proxima Centauri b, the Earth-like planet orbiting the red dwarf Proxima Centauri may have oceans, scientists say. The planet was discovered in August 2016 and caused excitement because it’s in the habitable zone of its star, and it’s rocky. And it’s in the Alpha Centauri, the closest star system to us!

Researches of France’s National Center for Scientific Research (CNRS) have calculated the size and surface properties of the planet and concluded it may be an “ocean planet” similar to Earth. There are possibilities, though, it may have continents and oceans like Earth, or its entire surface may be covered by a massive ocean.

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Scale of the Solar System (and the first flybys of planets)

Previously I posted two articles titled “If The Moon Were Only 1 Pixel – A Tediously Accurate Map Of The Solar System“, and “A Scale Model of Solar System Drawn in the Desert and the Result is Stunning“. Since the human brain cannot deal with the really large numbers, these articles provide an amazing way to understand how big actually our Solar System is.

Now, I decided to put the Solar System into scale as an infographic. You can see a scaled Solar System below, the planets’ distances from the Sun, and the first flybys over them. Plus some statistics about the planets and our home planet, the Earth.

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Proxima Centauri b: Did We Find Earth’s Cousin?

On August 24, 2016, a group of scientists led by Dr. Guillem Anglada-Escude at the Queen Mary University of London, announced the discovery of a terrestrial exoplanet orbiting the red dwarf Proxima Centauri, the nearest known star to the Sun. Proxima Centauri is a Latin idiom, meaning “nearest (star) of Centaurus” (1). The new planet is named Proxima Centauri b and it is predicted to be orbiting within the habitable zone!

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Where Earth’s water came from?

Earth is a blue marble in the space: the water, gives our planet its blue color: about 71 percent of the Earth’s surface is water-covered. There is roughly 326 million cubic miles (1.332 billion cubic kilometers) water on the Earth’s surface. Almost 97% of that water is salty (ocean water). But where all that water came from?

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