It’s Getting Hot on Jupiter

Observations with the Subaru Telescope, a Japanese 8-m telescope on Mauna Kea, Hawaii, show that the aurorae at Jupiter’s poles are heating the atmosphere of the gas giant, and that it is a rapid response to the solar wind.

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Aurorae at Earth’s poles occur when the energetic particles blown out from the Sun, the solar wind, interact with and heat up the gases in the upper atmosphere.

The same thing happens at Jupiter, but the new observations show the heating goes 2-3 times deeper down into its atmosphere than on Earth, into the lower level of Jupiter’s stratosphere (upper atmosphere).

Understanding how the Sun’s outpouring of solar wind interacts with planetary environments is key to better understanding the nature of how planets and their atmospheres evolve.

What is startling about the results is that scientists were able to associate the variations in the solar wind and the response in Jupiter’s stratosphere, and that the response to these variations is so quick for such a large area.

Within a day of the solar wind hitting Jupiter, the chemistry in its atmosphere changed and its temperature rose, the astronomers found.

Such heating and chemical reactions may tell us something about other planets with harsh environments, and even early Earth.

The results appear in the journal Nature Astronomy.

The First Pic of a Black Hole

Scientists from a global collaboration of telescopes announced Wednesday that they have captured the first-ever photo of a black hole.

The collaboration, called the Event Horizon Telescope, is a global network of eight telescopes that has been working for two years to capture the first image of a black hole, by combining data from the eight telescopes and “creating a virtual Earth-sized telescope.”

“We have seen what we thought was unseeable,” Shep Doeleman, the director of the EHT, said during a news conference Wednesday.

In 2017, the group embarked on a week long observation spanning telescopes in four continents, capturing data from two black holes: one in Sagittarius A*, located at the center of the Milky Way galaxy, and the other in the Messier 87 galaxy, in the constellation Virgo.

MIT’s Katie Bouman with the hard drives used to store the black hole image data. 

Passing Gas on Mars

Methane gas is periodically detected in the atmosphere of Mars. This was once considered implausible and perplexing, but it is now widely accepted by planetary scientists. Why the methane is there is still a mystery. It could point to present-day Martian microbes living in the rocks below the surface.

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Scientists working with the ESA’s Mars Express orbiter reported that in the summer of 2013, the spacecraft detected methane within Gale Crater, a 96-mile-wide depression near the Martian equator.

In the same summer of 2013, NASA’s Curiosity rover also measured a marked rise of methane in the air that lasted over two months.

The presence of methane is significant because the gas decays quickly. Calculations indicate that sunlight and chemical reactions in the thin Martian atmosphere would break up the molecules within a few hundred years, so any methane detected must have been created recently.

It could have been created by a geological process known as serpentinization, which requires both heat and liquid water. Or it could be a product of life, specifically methanogens, microbes that release methane as a waste product. Methanogens thrive in places lacking oxygen, such as rocks deep underground and the digestive tracts of animals.

Even if the source of the methane turns out to be geological, the hydrothermal systems that produce the emissions would still be prime locations to search for signs of life.

A newer European Mars spacecraft, the Trace Gas Orbiter, which has a more sophisticated methane detector, has been in orbit since 2017, but no results have been reported as of yet.

Tremors on Mars

Since NASA’s InSight lander, um landed on Mars at the end of last year, the plucky surface probe has spent months getting carefully situated so that its special seismometer could listen for “marsquakes” a neologism for earthquakes that occur on Mars, rather than Earth, as you probably guessed.

Observations of marsquakes will help determine just what’s going on inside of Mars, and to what extent it is still a geologically active world. We know Mars was very geologically active in the past; it has the tallest mountain of any planet in the solar system.

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While InSight hasn’t heard mars-shaking marsquakes yet, Scientists have revealed that the lander’s instrument has detected a different kind of rumbling known as microseisms. They are the first of their kind to be detected on another planet.

The new noises are caused by low-frequency pressure waves from atmospheric winds. On Earth, microseisms are caused by the ocean, storms and tides. Researchers working on InSight hope to hear a real marsquake within one month.

InSight’s other instruments have been providing scientists with troves of data. Indeed, since mid-February, InSight has issuing weather reports from Mars.

Ultimately, InSight’s science will help contribute to an overall picture of the history of the solar system, and how Mars, Earth and the other planets formed and evolved. The Auxiliary Payload Subsystem (APSS) lets InSight provide more frequent weather information than any previous mission to Mars.

InSight’s science will help contribute to an overall picture of the history of the solar system, and how Mars, Earth, and the other planets formed and evolved.

A Better Way to Look

K-type dwarf stars are dimmer than the Sun but brighter than faint stars. These stars live for a very long time, 17 to 70 billion years, compared to 10 billion years for the Sun. This gives plenty of time for life to evolve on any planets in their habitable zones. Also, they have less extreme activity in their youth than M-type stars (red dwarfs), the most common star type in the Milky Way Galaxy.

K-stars may be in a ‘sweet spot’ between Sun-analog stars and M-type stars astronomers at NASA’s Goddard Space Flight Center and writers of a paper published in the Astrophysical Journal Letters.

Scientists consider the simultaneous presence of oxygen and methane in a planet’s atmosphere to be a strong biosignature because these gases like to react with each other, destroying each other. So if they are present in an atmosphere together, that implies something is producing both of them quickly, quite possibly life.

However, because exoplanets are so remote, there needs to be significant amounts of oxygen and methane in an exoplanet’s atmosphere for it to be seen by observatories on Earth. The researchers found that the oxygen-methane biosignature is likely to be stronger around a K-type star than a Sun-like star.

This stronger oxygen-methane signal has also been predicted for planets around M-type stars, but their high activity levels might make M-stars unable to host habitable worlds. K-type stars can offer the advantage of a higher probability of simultaneous oxygen-methane detection compared to Sun-like stars without the disadvantages that come along with an M-star host.

Additionally, exoplanets around K-type stars will be easier to see than those around Sun-like stars simply because K-stars are dimmer. The Sun is 10 billion times brighter than an Earth-like planet around it. That’s a lot of light you have to suppress if you want to detect an orbiting planet. A K-star might be ‘only’ a billion times brighter than an Earth-like planet orbiting it.