It Doesn’t Take Much to Get Tilted Planets

Earth's axial tilt (or obliquity) and its relation to the rotation axis and plane of orbit. Credit: Wikipedia Commons

Chinese and Indian astronomers were the first to measure Earth’s axial tilt accurately, and they did it about 3,000 years ago. Their measurements were remarkably accurate: in 1120 BC, Chinese astronomers pegged the Earth’s axial tilt at 24 degrees. Now we know that all of the planets in the Solar System, with the exception of Mercury, have some tilt.

While astronomers have puzzled over why our Solar System’s planets are tilted, it turns out it’s rather normal.

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ALMA Takes Next-Level Images of a Protoplanetary Disk

This ALMA image of the young star HL Tauri shows rings of dust surrounding the star. The line patterns show the orientation of polarized light. It's the deepest dust polarization image of any protoplanetary disk captured thus far, revealing details about the dust grains in the disk. Credit: NSF/AUI/NRAO/B. Saxton/Stephens et al.

The ESO’s Atacama Large Millimeter/submillimeter Array (ALMA) is perched high in the Chilean Andes. ALMA is made of 66 high-precision antennae that all work together to observe light just between radio and infrared. Its specialty is cold objects, and in recent years, it has taken some stunning and scientifically illuminating images of protoplanetary disks and the planets forming in them.

But its newest image supersedes them all.

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Astronomers See the Afterglow Where Two Ice Giant Planets Collided

This artist's illustration is a visualization of the huge, glowing planetary body produced by a planetary collision. In the foreground, fragments of ice and rock fly away from the collision and will later cross in between Earth and the host star which is seen in the background of the image. Image Credit: Mark Garlick

What would happen if two giant planets collided? It would be terrifying to behold if it happened in our Solar System. Imagine if Neptune and Uranus slammed into each other. Picture the chaos as a new super-heated object took their places, and clouds of debris blocked out the Sun. Think of the monumental destruction as objects are sent careening into each other.

Astronomers spotted the aftermath of a gigantic planetary collision like this in a distant solar system. From a safe distance, they were surprised and intrigued rather than terrified. Now, they intend to keep watching as the aftermath unfolds.

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When did the First Continents Appear in the Universe?

Continents might be necessary for life, especially complex life. This image shows super-continent Pangaea during the Permian period (300 - 250 million years ago). Credit: NAU Geology/Ron Blakey

On Earth, continents are likely necessary to support life. Continents ‘float’ on top of the Earth’s viscous mantle, and heat from the planet’s core keeps the mantle from solidifying and locking the continents into place.

The core is hot because of the presence of radioactive elements that came from neutron star collisions. It should be possible to calculate when the first continents formed in the Universe.

So that’s what one researcher did.

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JWST Sees Newly Forming Planets Swimming in Water

This artist’s concept portrays the star PDS 70 and its inner protoplanetary disk. New measurements by NASA’s James Webb Space Telescope have detected water vapor at distances of less than 100 million miles from the star – the region where rocky, terrestrial planets may be forming. This is the first detection of water in the terrestrial region of a disk already known to host two or more protoplanets, one of which is shown at upper right. Credit: NASA, ESA, CSA, J. Olmsted (STScI)

One big question about Earth’s formation is, where did all the water come from? New data from the James Webb Space Telescope (JWST) shows newly forming planets in a system 370 light-years away are surrounded by water vapor in their orbits. Although astronomers have detected water vapor in protoplanetary disks before, this is the first time it’s been seen where the planets are forming.

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One in Ten Stars Ate a Jupiter (Or Bigger)

This illustration shows a Jupiter-mass exoplanet getting perilously close to its star. Eventually, the star will engulf the planet, something that happens in many stars' lives as they leave the main sequence. Image Credit: C. Carreau / ESA.

In space, cataclysmic events happen to stars all the time. Some explode as supernovae, some get torn apart by black holes, and some suffer other fates. But when it comes to planets, stars turn the tables. Then it’s the stars who get to inflict destruction.

Expanding red giant stars consume and destroy planets that get too close, and a new study takes a deeper look at the process of stellar engulfment.

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Astronomers Watch a Star Gulp Down One of its Planets

A distant Sun-like star will leave the main sequence behind, ending its life of fusion. Then it'll expand into a red giant, totally destroying its four planets. Image Credit: fsgregs Creative Commons Attribution-Share Alike 3.0 Unported

A star like our Sun only shines the way it does because of its intrinsic balance. Stars are massive, and the inward gravitational pressure from all that mass acts to contain the outward thermal pressure from all the fusion inside the star. They are in equilibrium, or on the main sequence if you like, and the result is a spherical mass of plasma that holds its shape and emits radiation with relative stability for billions of years. Like our Sun.

But eventually, stars teeter over the edge and lose their balance. Stars like our Sun will expand, take on a malevolent red hue, and begin to destroy anything that comes within their grasp.

Like a planet.

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A Rogue Earth and Neptune Might Have Been Found in Older Data

An artist's illustration of a rogue planet, dark and mysterious. Image Credit: NASA

Scientists have found what appear to be rogue planets hidden in old survey data. Their results are starting to define the poorly-understood rogue planet population. In the near future, the Nancy Grace Roman Space Telescope will conduct a search for more free-floating planets, and the team of researchers developed some methods that will aid that search.

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A White Dwarf is Surrounded by Torn-up Pieces of its Inner Planets and its Kuiper Belt

This illustration shows a white dwarf star siphoning off debris from shattered objects in a planetary system. Image Credit: NASA, ESA, Joseph Olmsted (STScI)

What will happen to our Sun?

In several billion years, it’ll cease fusion, shrivel into a white dwarf, and emanate only remnant heat. There it’ll sit, dormant and comatose.

But the Sun anchors the entire Solar System. What will happen to Earth? To the rest of the planets? To the rest of the objects in the Solar System?

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Compare Sand Dunes Across the Solar System, From Venus to Pluto

"Furrowed" dunes around Mars South Pole. Credit: NASA/JPL-Caltech/University of Arizona

One of the most interesting things we can learn from studying the planets and bodies of our Solar System is how much they have in common. Mars has polar ice caps and features that formed in the presence of water. Venus is similar to Earth in size, mass, and composition and may have once been covered in oceans. And countless icy bodies in the Solar System experience volcanism and have active plate tectonics, except with ice and water instead of hot silicate magma. Another thing they have in common, which may surprise you, is sand dunes!

According to a new study by researchers from Monash University and the University of Pennsylvania, multiple planets in our Solar System have sand dunes on their surfaces – just in different forms! These features further indicate that the mechanisms for dune formation are ubiquitous throughout the Solar System. These findings could lead to new methods for assessing the surface conditions of planets and moons and could have significant implications for future robotic and crewed missions to study them up-close.

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