My Science School

Sometimes a sudden, rapid, and intense variation in brightness is seen on the Sun. That is a solar flare. A solar flare is a sudden explosion of electromagnetic energy caused by reorganising of magnetic field lines near sunspots. (Sunspots are dark blotches that form on the surface of the Sun, where the magnetic fields are particularly strong). The flares are seen as bright areas on the Sun and they can last from minutes to hours. We typically see a solar flare by the photons (or light) it releases, at almost every wavelength of the spectrum. The current solar flares are just part of the Solar Cycle 25, which began in December 2019.

Even though the solar flare stays close to the Sun (relatively speaking), the material thrown in to space by these explosions is radioactive. It is potentially dangerous to spacecraft and especially to people in space. Solar flares emit radiation across virtually the entire electromagnetic spectrum, from radio waves at the long wavelength end, through optical emission to x-rays and gamma rays at the short wavelength end. This radiation can corrode equipment, overload cameras or MICAS, and expose humans to dangerous levels of radiation.

Solar flares are classified as A, B, C, M or X according to the peak flux (in watts per square metre, W/m2) of 1 to 8 Ångströms X-rays near Earth, as measured by XRS instrument on-board the GOES-15 satellite which is in a geostationary orbit over the Pacific Ocean.

The A & B-class are the lowest class of solar flares. They are very common and not very interesting. C-class solar flares are minor solar flares that have little to no effect on Earth. Only C-class solar flares which are long in duration might produce a coronal mass ejection but they are usually slow, weak and rarely cause a significant geomagnetic disturbance here on Earth.  M-class solar flares are what we call the medium large solar flares. They cause small (R1) to moderate (R2) radio blackouts on the daylight side of the Earth.  X-class solar flares are the biggest and strongest of them all. On average, solar flares of this magnitude occur about 10 times a year and are more common during solar maximum than solar minimum. Some (mostly stronger) solar flares can launch huge clouds of solar plasma into space which we call a coronal mass ejection. When a coronal mass ejection arrives at Earth, it can cause a geomagnetic storm and intense auroral displays.

Credit : Space Weather Live

Picture Credit : Google

Sunlight only takes 490 seconds (8 minutes 10 seconds) to reach Earth. And then at the most distant point, it takes 507 seconds (8 minutes 27 seconds) for sunlight to make the journey. However, this time is variable because the earth is constantly orbiting the sun on a course which is elliptical, ie uneven.The distance between the earth and the sun is 149.6 million kilometres (that’s 92.95 million miles). The speed of light is 299,792,458 metres per second (299,792.458 kilometres per second).  Once they reach the surface and escape they travel fast. But they are made via fusion reactions right at the sun’s core and VERY slowly work their way out.

Credit : Google 

Picture Credit : Google 

Proxima Centauri, closest star to our sun.  The star Proxima Centauri isn’t visible to the eye, but it’s one of the most noted stars in the sky. That’s because it’s part of the Alpha Centauri star system, home to three known stars and the closest stellar system to our sun. Of the three stars in Alpha Centauri, scientists believe Proxima is closest to our sun, at 4.22 light-years away. Astronomers have discovered two planets for Proxima so far. It also has massive solar flares and might even be the source of a mysterious radio signal. 

‘Usually, when stars are so close to Earth, they appear bright in our sky. Consider the star Sirius, for example, in the constellation Canis Major. Sirius is the brightest star in Earth’s sky, at just 8.6 light-years away. So why isn’t Proxima Centauri, at 4.22 light years away, even brighter? Instead of being bright, Proxima isn’t visible at all the the eye alone.

And the reason is that Proxima Centauri is so small. It’s what’s called a red dwarf star, one of the most common sorts of stars in our Milky Way galaxy. It contains only about an eighth of our sun’s mass. Faint red Proxima Centauri is only 3,100 Kelvin (5,100 degrees F or 2,800 C) in contrast to 5,778 K for our sun. So Proxima is 500 times less bright than our sun.

Credit : Earthsky

Picture Credit : Google 

Sirius, also known as the Dog Star or Sirius A, is the brightest star in Earth's night sky. The name means "glowing" in Greek — a fitting description, as only a few planets, the full moon and the International Space Station outshine this star.

Because Sirius is so bright, it was well-known to the ancients. But the discovery of a companion star, Sirius B, in 1862 surprised astronomers. The star that you can see with the naked eye is called Sirius A, or sometimes just Sirius. 

Sirius B is 10,000-times dimmer than Sirius, according to NASA(opens in new tab). It's so dim, and therefore so difficult to see from Earth, that astronomers couldn't estimate its mass until 2005, thanks to data from the Hubble Space Telescope.

Credit : Space.com

Picture Credit : Google 

The first photograph of our sun was taken by French Physicists Louis Fizeau and Leon Foucault on April 2nd, 1845. The snapshot was captured using the daguerreotype process (don't tell Bayard) and resulted after 1/60 of a second. If you observe the photograph carefully, you can spot several sunspots. That vintage photo of the Sun shows our star’s relatively sharp edge as well as a handful of sunspots. The spots are pretty big, roughly as wide as Jupiter (for comparison, the Sun is 1.4 million kilometers across).

If we want to click a picture of the sun, we pick up a camera or a smartphone and snap it in all its magnificence. While it is as easy as that currently, capturing the sun was no easy feat even a couple of centuries ago.

In fact it was only on April 2, 1845 that the first surviving detailed photographs of the surface of the sun were taken. French physicists Armand-Hippolyte-Louis Fizeau and Jean-Bernard-Leon Foucault were the two men who made it happen. Fizeau and Foucault came together through their interest in the Daguerre photographic process that had been recently invented. Even though photography was still in its infancy and its mainstream use in astronomy was still decades away, Fizeau and Foucault decided to turn their camera towards the sun.

While they came together for this project late in the 1830s, adapting the then existing photographic process to astronomy was no easy feat. It took them years, but on April 2, 1845, they succeeded in what they set out to do - capturing the sun in considerable detail. These images are the first surviving detailed daguerreotype photographs of the surface of the sun.

Picture Credit : Google 

Astronauts can grow up to 3 per cent taller during the time spent living in microgravity, NASA scientists say. That means that a 6-foot-tall person could gain as many as 2 inches while in orbit. While scientists have known for some time that astronauts experience a slight height boost during stays on the International Space Station, NASA is only now starting to use ultrasound technology to see exactly what happens to astronauts' spines in microgravity. Past studies have shown that when the spine is not exposed to the pull of Earth's gravity, the vertebra can expand and relax, allowing astronauts to actually grow taller. That small gain is short lived. Once the astronauts return to Earth, their height returns to normal after a few months. Now, astronauts will use a ultrasound device on the station that allows more precise musculoskeletal imaging to scan each other's backs to see exactly what their spines look like after 30, 90 and 150 days in microgravity. Researchers will see the medical results in real time as the astronaut take turns scanning the spines of their crewmates.

A better understanding of the spine's elongation in microgravity could help physicians develop more effective rehabilitation techniques to aid astronauts in their return to Earth's gravity following space station missions.

Picture Credit : Google