It’s Cold Out There

Image result for Pluto

Pluto is the smallest, coldest and most distant dwarf planet with an atmosphere in the Solar System. It orbits the Sun every 248 years, and its surface temperature is between -378 and -396 degrees Fahrenheit (-228 to -238 degrees Celsius). Its atmosphere consists of nitrogen, with traces of methane and carbon monoxide.

Scientists aimed to record the seasonal evolution of Pluto’s surface pressure by observing ground-based stellar occultations to gain the atmosphere’s profile including density, pressure and temperature. They were able to construct seasonal models of Pluto and how it responds to changes with the amount of sunlight it receives as it orbits the Sun. What they found was when Pluto is farthest away from the Sun, and during its winter in the northern hemisphere, the nitrogen freezes out of the atmosphere.

The atmospheric pressure has tripled over the past three decades, but as the dwarf planet orbits, the modeling showed that most of the atmosphere would condense to the point that there is almost nothing left.

What the predictions show is that by 2030 the atmosphere is going to frost out and vanish around the entire planet. If it does freeze over, Pluto may appear brighter in the sky due to sunlight reflecting from it.

The findings will be published in the journal Astronomy & Astrophysics.

The Fate of the Earth

If it weren’t for the sun constantly showering us with energy, there would be no life on Earth. But eventually the sun will run out of fuel, expand into a red giant and finally collapse into faint, white dwarf. What will happen to us and the other planets in the solar system when the sun dies? It’s not entirely clear.

Scientists think that they have spotted the possible core remnant of a planet orbiting the white dwarf SDSSJ122859.93+104032.9, residing some 410 light years away. The results, published in Science, offer important clues about the fate of the planets in our solar system.

The planetary fragment produced a stream of gas that could be detected by spectrometers. Researchers spotted it orbiting the star by looking at how its spectrum shifted in color as the body moved towards and away from Earth. This change in color is called a doppler shift, which is essentially a stretching or squashing of waves because of motion. It is similar to the pitch of the sound of an ambulance being higher when it is heading towards you, and lower when it is moving away.

The object completed one passage around its host star in just over two hours, orbiting at a distance that is smaller than the radius of the sun in a disc of gas and dust.

The discovery is surprising, since scientists didn’t think anything could survive so close to a white dwarf. A white dwarf is only about the size of the Earth but it contains around 60-70% of the sun’s mass, making it extremely dense. If a body orbits too close to a white dwarf, its immense gravity will rip it apart. This was likely the fate of the material that formed the disc around it.

So how did this object survive without getting ripped apart? It would have to either be very dense itself or have some amount of internal strength holding it together. Scientists calculated that it has a maximum diameter of 720km, which is the size of a small minor planet. The dwarf planet Ceres in our solar system has a diameter of 946km by comparison.

The origin of this object remains a mystery. One possibility is that this is the core of a minor planet that was pushed close to the white dwarf by a larger planet further out in the remnant planetary system, like a Jupiter. As the minor planet passed close to the white dwarf, its crust and mantle layers would have been ripped away.

All that would be left of the planet would be its dense, iron-dominated core. This kind of object is quite common, with one famous resident in our own solar system: the asteroid 16-Psyche.

Systems such as the one just discovered can help us understand the future of our own planetary system. In about five billion years, the sun will start to expand into a red giant. At this point, it will engulf Mercury, Venus and most likely Earth, unless we manage to move our planet into a wider orbit, which should be possible in theory. However, Mars, the asteroid belt and the rest of the solar system will survive engulfment and continue orbiting the sun as it then collapses into a white dwarf.

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During this process, planets like Jupiter could also scatter asteroids, comets or even minor planets towards the white dwarf. There they would undergo partial or complete disruption, forming a disc like the one just discovered. It is unlikely that any living organisms on planetary or moon fragments could survive this process. Even if they did, they would struggle to live on in the faint light of a white dwarf.

This is not only the solar system’s fate, but that of practically all known exoplanet systems. In the much much closer future, scientists hope to find more planetary bodies around other white dwarfs. There are six candidate white dwarfs that are orbited by discs made of dust and gas, and researches want to test whether these discs are the “smoking gun” for the presence of minor planets. The more such planets are found, the more that can be learned about what happens to a planetary system as its star dies.

Go The Distance

A couple of weeks ago, astronomers spotted what they believe is the most distant object in the solar system  a dwarf planet some 9.5 billion miles from the sun. Dubbed V774104, the object is between 310 miles and 620 miles across about half Pluto’s size and about three times farther from the sun.

V774104 is about 103 times farther from the sun than Earth, and scientists’ early guess is that it is part of a rare group of ‘sednoids,’ objects whose orbital paths exist entirely outside the Kuiper Belt and extend into the Oort Cloud, the boundary of our solar system. Only two confirmed sednoids exist, Sedna and 2012 VP113 but scientists suspect there are more.

If V774104 proves to be one, it would provide astronomers with further support for the theory that an undiscovered Planet X is lurking in the outer fringes of our solar system. The gravitational pull from a Planet X would help explain the highly elliptical orbits of the sednoids.

Until astronomers spotted V774104, the dwarf planet Eris was considered the solar system’s most distant object. Eris is about 97 astronomical units from the sun, while V774104 is 103 AUs (the unit of length equal to the distance between Earth and the sun).

Tour the Solar System AT THE SPEED OF LIGHT

An eye-opening new video really puts the sheer size of the solar system in perspective. It shows that even if you travel at the speed of light (186,000 miles per second), the trek from the sun to the Earth and other planets takes a really long time.

The 45-minute-long video, created by Los Angeles-based artist Alphonse Swinehart and posted on Vimeo Jan. 26, starts at the sun and zooms out into the solar system. You reach the Earth and our moon at around 8:20, and the journey ends after reaching Jupiter and its moons at around 43:20.

Watch and feel insignificant: