Here's what you get from 20 years of staring at the Sun

Wednesday, December 2, 2015, 1:41 PM - The Solar and Heliospheric Observatory, aka SOHO, celebrates 20 years in space today, with an incredible new video highlighting some of the most amazing moments of the mission.

It's dangerous for us to stare at the Sun, for any length of time.

To get around that danger, to perform the important task of tracking solar activity, NASA and the European Space Agency have launched satellites into orbit. SOHO, the Solar and Heliospheric Observatory, is a joint mission between the two agencies, and today - December 2, 2015 - marks the mission's 20th anniversary!

According to NASA:

After 20 years in space, ESA and NASA’s Solar and Heliospheric Observatory, or SOHO, is still going strong. Originally launched in 1995 to study the sun and its influence out to the very edges of the solar system, SOHO revolutionized this field of science, known as heliophysics, providing the basis for nearly 5,000 scientific papers. SOHO discovered dynamic solar phenomena such as coronal waves, solar tsunamis and sun quakes, and found an unexpected role as the greatest comet hunter of all time — reaching 3,000 comet discoveries in September 2015.

Sitting out in space, at Lagrange Point 1 (L1) beyond the Moon's orbit and directly between the Earth and the Sun, SOHO enjoys an uninterrupted view of our parent star. From there, it providing us with near-real time imagery of sunspots, solar flares, prominences and coronal holes, very similar to what we see from NASA's Solar Dynamics Observatory. SOHO, however, goes beyond that, to also image activity around the Sun, capturing coronal streamers radiating out from the Sun's disk and coronal mass ejections blasting out into space.

Here, SOHO shows off multiple sunspots from October 28, 2003 (left), and a solar flare (right) in the upper right portion of the Sun's face from April 3, 2001. The image on the right filters out all wavelengths of light except those around 304 Angstroms (0.0000000304 m), thus showing only extreme ultraviolet light at temperatures around 50,000 Kelvin. Image credits: SOHO (ESA/NASA).

In these images, a bright solar flare spied on May 2, 1998, using the 195 Angstrom filter (left), and a large prominence that was captured on September 14, 1999 (right), using the 304 Angstrom filter. Also visible on the left, the darker region at the Sun's north pole is a large coronal hole, where the Sun's magnetic field has opened up, allowing solar particles to stream away from the surface at high speed. The 195 Angstrom view, shown in green, filters out all light but wavelengths around 0.0000000195 m, which is also in the extreme ultraviolet, but at temperatures more like 1.5 million Kelvin. This view is coloured green to differentiate it from the other filtered views SOHO provides. Image credits: SOHO (ESA/NASA).

To look at the space surrounding the Sun, SOHO uses an instrument known as LASCO - the Large Angle and Spectrometric Coronagraph. This coronagraph uses a small disk at the centre of its view to block out the direct light from the Sun. Just like holding up your hand to shield your eyes from bright sunlight, this tiny disk allows LASCO to image the space directly around the Sun, to pick up fainter features.

Shown above are LASCO's two views - a close-up view of the solar environment on the left and a zoomed out look on the right. These two views, from August 16, 2001, show a large coronal mass ejection (CME) - billions of tons of solar matter blasted away from the Sun during a solar flare. The bright lines radiating out from the disk in the left view are coronal streamers - solar particles flowing out from the Sun at high speed. The arcing filaments to the left and lower right of the disk are the CME. The "snowy" look to the right-hand image is due to high-energy particles from the Sun striking the detector.

The past 20 years haven't been without troubles or incidences.

Karl Battams, an astrophysicist and computational scientist at the US Naval Research Laboratory (NRL) in Washington DC, who works closely with SOHO's data on a regular basis, relates how SOHO went offline for a month and a half in the middle of 1998.

The year after, it suffered another failure, but came back strong.

Interested in seeing more from SOHO? Check out Battam's Sungrazer Project page and NASA's SOHO space weather site.

What else is going on?

Orbital Sciences is launching their next Cygnus cargo spacecraft to the International Space Station. Liftoff is scheduled for 5:55:45 p.m. EST on Thursday, December 3, from Cape Canaveral in Florida.

This is the first Cygnus launch following the disastrous attempt back on October 29, 2014, which ended with the booster rocket and spacecraft exploding just moments after takeoff.

According to NASA:

This delivery will support significant research being conducted off the Earth to benefit the Earth, including investigations in advanced and automated data collection and in the behavior of gases, liquids and burning textiles in microgravity.

Forecasters currently give a 60 per cent chance of favourable weather for the launch, which will be shown live via NASA TV.

CRS-4 sits ready on the launch pad at Space Launch Complex 41, Cape Canaveral Air Force Station, Florida, on December 2, 2015. Credit: NASA

Sources: NASA | NASA/ESA | US Navy | NASA

Related Video: NASA's Solar Dynamics Observatory celebrated its 5th anniversary in Feb 2015. Check out the highlights from the mission below.