Mercury’s sodium tail
Mercury has a protracted flowing tail trailing away from the sun, very similar to a comet, seen in long-exposure images. Scientists first predicted Mercury had a tail within the Nineteen Eighties, then found it in 2001. NASA’s Messenger mission additionally revealed many tail particulars between 2011 and 2015 when it orbited Mercury. These days, astrophotographers right here on Earth are in a position to seize nice photographs of Mercury’s tail with the precise tools and somewhat know-how. Steven Bellavia shares his pictures and methods for capturing this uncommon phenomenon, beneath.
Why does Mercury have a tail?
The reply lies partly in sodium atoms. These atoms are free of Mercury’s floor by the push of daylight and micrometeorite impacts. The sodium atoms from the floor are blasted into Mercury’s environment and into space, the place they kind the planet’s tail. Messenger found that daylight scatters off the sodium atoms, giving them a yellow or orange glow. The sun isn’t simply selectively blowing sodium off the floor of Mercury, although. Mercury’s tail is made up of many components, however sodium will get the highest billing as a result of it does such an excellent job of scattering yellow mild. This permits the tail to look on long-exposure images.
And the way massive is Mercury’s sodium tail? It’s roughly 100 occasions longer than the diameter of Earth!
The best way to {photograph} Mercury’s tail
Mercury’s tail is brightest inside 16 days of perihelion, the planet’s closest level to the sun. Mercury reaches perihelion each 88 days (it takes 88 days to orbit the sun as soon as). Within the picture at prime, Steven Bellavia captured Mercury on October 11, 2022, 5 days previous Mercury’s most up-to-date perihelion on October 6, 2022.
Bellavia instructed EarthSky that an article at Spaceweather.com on Could 10, 2021, impressed him to strive photographing Mercury’s sodium tail utilizing a 589 nanometer (nm) wavelength filter that lets the sodium mild signature by way of. After studying about it, he was desperate to strive it for himself. He defined:
On the morning of Wednesday, Could 11, 2021, I ordered a 589 nm narrowband filter, with 10 nm of bandpass [the wavelength range of the filter], from Edmund Optics. A good friend who owns a 3D printer printed me two rings that I designed to carry the filter, because the filter didn’t include customary mounting utilized in astronomy. I used the brand new setup inside hours of getting all of it collectively.
Ingenious!
Bellavia’s 1st pictures of Mercury’s sodium tail
Bellavia first captured pictures of Mercury’s tail on each Could 13 and 14, 2021. He used a monitoring German equatorial mount affixed with a Canon 100mm lens and the filter mounted in entrance of the lens. On the primary evening he took 30 exposures of 30 seconds every, whereas on the second evening he took 20 exposures of 60 seconds every utilizing a Borg 90mm refractor. He stated:
On the second evening, having seen the outcomes from my first try, I spotted that it might be higher to have the telescope and mount observe on Mercury itself, because the tail is faint, and all photons collected have to land as continuously as attainable on the identical pixels in every particular person picture to disclose it. Additionally observe that on each nights, I might have favored to have taken many extra pictures, however I wanted to attend for the background sky to be darkish sufficient to disclose the tail. However Mercury was additionally setting presently, both behind land or into clouds close to the horizon.
Even with these limitations, Bellavia’s pictures of Mercury’s sodium tail are outstanding. Learn extra about Bellavia’s digicam setting here and here at EarthSky Community Photos, and take a look at his setup and kit for photographing Mercury’s sodium tail at his web page on Flickr.
Pictures of Mercury’s tail
Sodium within the universe
Astronomers can use filters within the 589 nm vary to find out about extra objects than simply Mercury’s tail. The sun and comets are good targets for sodium filters. Astronomers have additionally seen sodium streaming from our moon, in addition to surrounding Jupiter in a haze after being blown off its moon Io. Discovery of sodium in different star methods permits scientists to find out about rocky exoplanets. They’ll even use sodium absorption bands to measure redshifts and the scale of the universe.
Thanks, Steven Bellavia, to your assist in assembling this data.
Have a photo of Mercury’s tail? Submit it to EarthSky Community Photos
Backside line: Mercury has a protracted tail flowing away from the sun. Photographers can seize it utilizing filters for the sodium vary of the electromagnetic spectrum. See nice pictures right here from Steven Bellavia.
