Starship Asterisk*

Mercury's Sodium Tail

Explanation: That's no comet. Below the Pleiades star cluster is actually a planet: Mercury. Long exposures of our Solar System's innermost planet may reveal something unexpected: a tail. Mercury's thin atmosphere contains small amounts of sodium that glow when excited by light from the Sun. Sunlight also liberates these molecules from Mercury's surface and pushes them away. The yellow glow from sodium, in particular, is relatively bright. Pictured, Mercury and its sodium tail are visible in a deep image taken last week from La Palma, Spain through a filter that primarily transmits yellow light emitted by sodium. First predicted in the 1980s, Mercury's tail was first discovered in 2001. Many tail details were revealed in multiple observations by NASA's robotic MESSENGER spacecraft that orbited Mercury between 2011 and 2015. Tails, of course, are usually associated with comets.

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The question might then be asked what sort of tail/trail might Venus and planet Earth be showing ?

While they are not being baked to a crisp like Mercury, a fair old trail of water vapour/clouds and gases
would be trailing behind. ? (even more like a comet ?)

Whether that would be visible from afar may be another matter ?

Wow, Mercury has a tail! And it's the same color as those boring sodium street lamps, too, because Mercury's tail is a kind of sodium lamp in space. Kind of. At least it is glowing from sodium.

Well, things have tails:

Wikipedia wrote about Mira the star's tail:

Ultraviolet studies of Mira by NASA's Galaxy Evolution Explorer (GALEX) space telescope have revealed that it sheds a trail of material from the outer envelope, leaving a tail 13 light-years in length, formed over tens of thousands of years. It is thought that a hot bow wave of compressed plasma/gas is the cause of the tail; the bow wave is a result of the interaction of the stellar wind from Mira A with gas in interstellar space, through which Mira is moving at an extremely high speed of 130 kilometres per second (290,000 miles per hour).

NASA Science wrote about the tail of galaxy D100:

Why is there long red streak attached to this galaxy? The streak is made mostly of glowing hydrogen that has been systematically stripped away as the galaxy moved through the ambient hot gas in a cluster of galaxies. Specifically, the galaxy is spiral galaxy D100, and cluster is the Coma Cluster of galaxies. The red path connects to the center of D100 because the outer gas, gravitationally held less strongly, has already been stripped away by ram pressure. The extended gas tail is about 200,000 light-years long, contains about 400,000 times the mass of our Sun, and stars are forming within it.

Finally, tail! Get that tail!


Ann

RocketRon wrote: ↑Tue May 03, 2022 4:32 am The question might then be asked what sort of tail/trail might Venus and planet Earth be showing ?

While they are not being baked to a crisp like Mercury, a fair old trail of water vapour/clouds and gases
would be trailing behind. ? (even more like a comet ?)

Whether that would be visible from afar may be another matter ?

Presumably any body with an atmosphere which is moving through a medium will have a tail. They've been detected around several of Jupiter's moons.

RocketRon wrote: ↑Tue May 03, 2022 4:32 am The question might then be asked what sort of tail/trail might Venus and planet Earth be showing ?

While they are not being baked to a crisp like Mercury, a fair old trail of water vapour/clouds and gases
would be trailing behind. ? (even more like a comet ?)

Whether that would be visible from afar may be another matter ?

The Earth apparently has an oxygen tail:

Science Alert wrote:

Solar Wind Is Blasting Earth's Oxygen Onto The Surface of The Moon

We all know that there's no air to breathe on the Moon, but new evidence suggests that the lunar surface is continually being showered by oxygen escaping Earth – and may have been for billions of years, since Earth's atmosphere developed.

Scientists have discovered that oxygen ions from Earth's atmosphere are transported to the Moon once a month, during a five-day window when the lunar satellite passes through our planet's protective magnetosphere. In this time, the Moon passes behind Earth, getting a short reprieve from the blast of the Sun's solar wind – and is sprinkled with a stream of material fleeing Earth instead.

While scientists had already suggested that traces of gases such as nitrogen could have ended up on the lunar surface after escaping our atmosphere, this is the first time researchers have shown that oxygen – one of the most important components of life on Earth – is also shipped direct to the Moon...

A planet that definitely has a tail is Mars:

NASA wrote:

NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) mission has identified the process that appears to have played a key role in the transition of the Martian climate from an early, warm and wet environment that might have supported surface life to the cold, arid planet Mars is today...

MAVEN measurements indicate that the solar wind strips away gas at a rate of about 100 grams (equivalent to roughly 1/4 pound) every second. "Like the theft of a few coins from a cash register every day, the loss becomes significant over time," said Bruce Jakosky, MAVEN principal investigator at the University of Colorado, Boulder. "We've seen that the atmospheric erosion increases significantly during solar storms, so we think the loss rate was much higher billions of years ago when the sun was young and more active.”

In addition, a series of dramatic solar storms hit Mars’ atmosphere in March 2015, and MAVEN found that the loss was accelerated. The combination of greater loss rates and increased solar storms in the past suggests that loss of atmosphere to space was likely a major process in changing the Martian climate.

Because Mars lacks a magnetic field, it can't deflect the charged particles of the solar wind that continually strips the Martian atmosphere. The Earth's atmosphere is much, much better protected than the atmosphere of Mars, because of our planet's magnetic field.

Ann

RocketRon wrote: ↑Tue May 03, 2022 4:32 am The question might then be asked what sort of tail/trail might Venus and planet Earth be showing

November 12, 2010: Did you know that the Earth has a dust tail? The Spitzer Space Telescope sailed right through it a few months ago, giving researchers a clear idea of what it looks like. That could be a big help to planet hunters trying to track down alien worlds.

It's extremely challenging – and usually impossible – to directly image exoplanets. They're relatively small and faint, hiding in the glare of the stars they orbit.

"A dust tail like Earth's could produce a bigger signal than a planet does. And it could alert researchers to a planet too small to see otherwise."

Earth has a dust tail not because the planet itself is particularly dusty, but rather because the whole solar system is. Interplanetary space is littered with dusty fragments of comets and colliding asteroids. When Earth orbits through this dusty environment, a tail forms in the rear, akin to swaths of fallen leaves swirling up behind a streetsweeper.

"As Earth orbits the sun, it creates a sort of shell or depression that dust particles fall into, creating a thickening of dust – the tail – that Earth pulls along via gravity," explains Werner. "In fact, the tail trails our planet all the way around the sun, forming a large dusty ring."


A computer simulation of Earth's dust tail/ring seen from a vantage point outside our solar system. Colors indicate density; purple is lowest, red is highest.
https://science.nasa.gov/science-news/ ... usttail/

The moon has a tail, and Earth wears it like a scarf once a month

Like a comet soaring through the cosmos, the moon is followed by a slender tail of irradiated matter — and Earth passes directly through it once a month.

According to a study published March 3 in the journal JGR Planets, the lunar tail is made of millions of sodium atoms blasted out of the lunar soil and into space by meteor strikes and then pushed hundreds of thousands of miles downstream by solar radiation. For a few days a month, when the new moon sits between Earth and the sun, our planet's gravity drags that sodium tail into a long beam that wraps around Earth's atmosphere before blasting into space on the opposite side.

The lunar tail is harmless and invisible to the naked eye. During those few new-moon days each month, however, the beam becomes visible to high-powered telescopes that can detect the faint orange glow of sodium in the sky. According to the study's authors, the beam then appears as a fuzzy, glowing spot in the sky opposite the sun, about five times the diameter of the full moon and 50 times dimmer than human eyes can perceive.



https://www.livescience.com/moon-has-a ... -tail.html

The tail of Venus

In rare events, the sheath of electrons and ions enveloping Venus in a height of 150 to 300 kilometres can expand into space like a tail. This exceptional deformation occurs on the planet’s night side, when the solar wind, the flow of charged particles from the Sun, nearly comes to a stop.


Gas trail in space: under normal conditions, Venus is surrounded by an ionosphere at a height of 150 to 300 kilometres. The induced magnetic fields – outlined here by yellow lines – bind it close to the planet. When the solar wind gets very weak, the ionosphere can expand into space. A kind of plasma tail is created (right) on the planet's night side.

https://www.nanowerk.com/news2/space/newsid=28719.php

Lots of tail out there! BTW The first article mentions how the Webb telescope is due to launch in 2014 !

Eric

I like your kitty video Ann! Did you ever see a cat or dog try to catch it's tail? It is amusing! fantastic view of Mercury's tail! Mercury's surface! Silly kitties!

Cool. So, the Moon gets oxygen from the Earth by passing through it's tail (per Ann's post) and the Earth gets sodium from the Moon by passing through it's tail (per XgeoX's post)! Panspermia writ small.

Also one correction: the link to the Messenger spacecraft site says:

Goal: Understanding Mercury, the smallest, densest and least-explored of the terrestrial planets

But apparently, Earth is actually denser than Mercury (though it shouldn't be!) -

https://bigthink.com/starts-with-a-bang/earth-densest-planet/ wrote:When it comes to the Solar System, the elements that make up each planet are determined by how they all formed. Closest to the Sun, the high temperatures, large amounts of solar radiation, and intense solar winds can easily kick the lightest elements off of any protoplanets that are forming. But farther away from the Sun, these factors have more difficulty expelling light elements. As a result, we wind up with planets that are disproportionately made of heavier elements the closer you get to the Sun, and that have lower density compositions — and large amounts of lighter atoms — the farther out we venture.

In the innermost part of the Solar System is the planet Mercury, which has only a negligible atmosphere and is made largely of rocky and metallic material. As we travel farther away from the Sun, atmospheres become common, as do greater proportions of lighter elements. If we were to look at each planet’s composition in terms of the atoms that make it up, Mercury would have the highest percentage of heavier elements, trailed by Venus and Earth, with Mars even farther behind.

You might think that would make Mercury the densest planet, but that’s not true at all. If you measure each planet’s mass and divide it by its volume, it turns out that Earth, not Mercury, is the densest world in our Solar System.
...

Click to view full size image

"Sunlight also liberates these molecules from Mercury's surface and pushes them away."

Is it possible that Mercury is becoming less and less of a planet (very, very, very slowly) over time because of this and other forces?

An emailer has pointed out that the sodium liberated from Mercury is actually in the form of atoms, not molecules. The text on the main NASA APOD page has therefore been updated to indicate this. I apologize for the oversight.
- RJN

This is not a new discovery. So how come it's all over the web all of a sudden? Maybe because of better imagery?