Sun Spotting

The solar flip has begun, the North Pole has already become the South Pole and the South is racing to become the North. Taking place every 11 years, this phenomenon has strong effects on the earth’s magnetic field, including magnetic storms, electric power grid tripping and TV and radio blank outs. As the sun is nearing solar maximum, you can expect increased sunspot activity, solar flares and coronal mass ejections.

Sunspots
Sunspots appear to be dark patches on the sun’s surface that occur when its magnetic field loops out of the solar surface and cools, thereby making the area less bright in comparison to the rest. Galileo Galilei, the first person to have viewed the sun through a telescope, saw sunspots too, but mistook the dark patches for clouds. Whereas, Chinese and Greek astronomers who saw them with the naked eye, before the invention of telescopes, rarely spoke of it. They were unwilling to admit that the sun could be imperfect with blemishes and could have an ever-changing face.
While the umbra (dark central area) of sunspots has a temperature of about 3,400 degrees Celsius, the surrounding photosphere is 1,500 degrees hotter.

Solar Prominences also called filaments, are arcs of gas that erupt from the surface of the sun and loop thousands of kilometres into space. They are held above the sun’s surface by strong magnetic fields and can last for weeks or months.


Flares & Prominences

Solar Flares are sudden eruptions of energy on the solar disk, from which radiation and particles are emitted. Like prominences they are ejected thousands of kilometres from the sun’s surface, but unlike them, flares last anywhere between a few minutes to a few hours.


Prominences, Flares & Loops

Faculae are bright cloud-like features located a few hundred kilometres above the photosphere near sunspot groups, seen in white light. Although Faculae occur all across the sun, they are generally visible near the solar limb.

Corona, the pearly white outermost layer of the sun’s atmosphere is only visible during total solar eclipses.  Viewing on a regular day requires space telescopes with a coronagraph or special ones that block out the sun’s photosphere.

Granulation is the cellular structure of the solar photosphere visible all over the sun in white light at a high resolution.

VIEWING TIPS
Exposure to the sun’s rays through any optical equipment can cause irreversable damage to your eyes, but you may not even realise or feel the pain as it happens. Therefore, extreme caution is necessary.

Naked Eye Viewing  - It is only possible in case of very large sunspots when the sun is close to the horizon during sunrise or sunset. But don’t stare for too long, it can permanently damage your eyes. You can also create your own pinhole camera–make a tiny hole on one side of an open shoebox, point it towards the sun and the projection of sunspots will be clearly visible on the otherside.

Projection Method – Use an open shoebox with a hole for the eyepiece and place a white card at the other end. Point a telescope or a pair of binoculars in the direction of the sun. But don’t peer through the telescope or the viewfinder, look along its side. Once it makes the shortest shadow, the image of the sun will get projected on the white card held behind the eyepiece.

Use Safe Solar Filters - The safest are the ones placed on the front end of the telescope; besides sunspots (its umbra and penumbra) they also enable you to see faculae, granulation and limb darkening at the edge of the sun’s disk. You can also get special telescopes with hydrogen-alpha filters that only allow red light of a particular wavelength to pass through, but they’re very expensive. For photography, coated glass or Mylar filters are the best. Finally, avoid eyepiece filters as they can suddenly crack on heating up.

Document Your Data - Make pencil sketches on a white card for observation records with four cardinal points (N,S,E,W) marked on a circle 150 mm in diameter. Note the time, date and place of observation and other details like sunspot numbers, latitude, longitude, your name, equipment details and viewing conditions. Send your observations to solar section of www.alpo-astronomy.org or www.aavso.org

Solar Observatories In India & Useful Websites - The 114-year-old Kodaikanal Solar Observatory and the Udaipur Solar Observatory in the middle of the Fateh Sagar Lake are two famous Indian observatories doing solar research work. Mumbai's Nehru Planetarium has a coelostat solar telescope that can be used to project an image of the sun inside the building and the sun is also observed with amateur radio telescopes.Find out more about how to observe the sun from www.solar-center.stanford.edu

Images by NASA