The ESA/NASA Solar and Heliospheric Observatory has discovered more than 3000 doomed comets that have passed close to the sun.
The Solar and Heliospheric Observatory, better known as "SOHO", is a joint project of the European Space Agency, or ESA, and NASA. Orbiting the sun at 1.5 million km, or 932,000 miles from Earth, the distant observatory has just discovered its 3000th comet-more than any other spacecraft or astronomer. And, just about all of SOHO's comets have been destroyed.
"They just disintegrate every time we observe one," said Karl Battams, a solar scientist at the Naval Research Labs in Washington, D.C., who has been in charge of running the SOHO comet-sighting website since 2003. "SOHO sees comets that pass very close to the sun-and they just can't stand the intense sunlight."
The overwhelming majority of SOHO's comet discoveries belong to the Kreutz family. Kreutz sungrazers are fragments from the breakup of a single giant comet thousands of years ago. They get their name from 19th century German astronomer Heinrich Kreutz, who studied them in detail. On average, a new member of the Kreutz family is discovered every three days. Unfortunately for these small comets, their orbits swoop perilously close to the sun.
There's only one Kreutz comet that made it around the sun – Comet Lovejoy. And we are pretty confident it fell apart a couple of weeks afterwards
Although SOHO's comets are rapidly destroyed, they nevertheless have great scientific value. For instance, the comets' tails are buffeted and guided by the sun's magnetic fields. Watching how the tails bend and swing can tell researchers a great deal about the sun's magnetic field.
Prior to the launch of SOHO in 1995, only a dozen or so comets had ever even been discovered from space, while some 900 had been discovered from the ground since 1761. SOHO has turned the tables on these figures, making itself the greatest comet hunter of all time.
But SOHO hasn't reached this lofty perch alone. The spacecraft relies on people who sift through its data. Anyone can help because SOHO's images are freely available online in real time. Many volunteer amateur astronomers scan the data on a daily basis for signs of a new comet. The result: 95% of SOHO comets have been found by citizen scientists.
Whenever someone spots a comet, they report it to Battams. He goes over the imagery to confirm the sighting and then submits it to the Central Bureau for Astronomical Telegrams, which gives it an official name.
And the name is…you guessed it. "SOHO."
While comets spotted from the ground are named after the person who first discovered them, comets first observed by a space-based telescope are named after the spacecraft. The 3000th comet discovered was named "SOHO-3000."
Naturally, it has already been destroyed. SOHO doesn't mind though. The Greatest Comet Hunter Ever has already moved on to the next sungrazer.
"SOHO-4000," anyone?
Astrophysics Big Questions About Small Worlds
Small Worlds hold keys to questions about our solar system and the origin of life on Earth.
Scientists who study the solar system tend to ask big questions: How was our solar system formed? Where did the building blocks of life come from? What hazards from above threaten life on our planet? To find answers, theyre looking more and more at small worlds.
What are small worlds? Asteroids for sure. Comets too. Also the many small satellites or moons that orbit large planets as well as the icy worlds at the distance of Pluto and beyond. Some have combined, only to be broken apart later by collisions and tidal forces. Others have gone largely untouched since the dawn of the solar system. Some carry water and organic compounds, others are almost entirely composed of metal. And all hold keys to questions about our solar system and the origin of life on Earth.
Water is key to life as we know it. Learning where water is found in our solar system provides pieces to the puzzle of understanding the origins of life. New Horizons recently surprised us by discovering a large abundance of water ice at Pluto. More surprises are in store, as New Horizons transmits the data from its January 1, 2019 flyby of the Kuiper Belt object 2014 MU69 back to Earth!
Small worlds can be found in a wide range of locations across the solar system, from the inner solar system all the way out to the Kuiper Belt. When they are studied together, these remnants of the early solar system can help tell the story of solar system formation.
Dawn recently completed a mission to the Main Asteroid Belt, visiting the dwarf planet Ceres and the Belts largest asteroid, Vesta. OSIRIS-REx has arrived at Bennu, a near-Earth asteroid about 1650 feet (500 m) across, and will return to Earth in 2023 with a sample so scientists can begin to understand Bennus origin and history. The Lucy mission will be traveling to six trojan asteroids, trapped in the orbit of Jupiter. These objects are the only remaining unexplored population of small worlds in the solar system. The Psyche mission will be visiting a metal object in the Main Asteroid Belt that could be the remnant core of a proto-planet similar in size to Vesta!
While those missions travel to their individual targets, NEOWISE, a repurposed space telescope in low-Earth orbit, has made infrared measurements of hundreds of near-Earth objects and tens of thousands of other small worlds in the solar system. These diverse worlds offer insights into how our solar system formed and evolved.
This is not your grandparents solar system and things are not as orderly as we once believed.
The data weve gleaned from these objects so far have changed the way we think about the origin of the planets. For example, the small worlds in the Kuiper Belt are leading us to think that Uranus and Neptune formed much closer to the Sun than where they reside now, then gradually moved to their current orbits.
The biggest misperception about small worlds? Their distance to each other. In the movies, they always show an asteroid belt with millions of rocks almost touching each other, whereas in reality there is much more empty space. You have to travel hundreds of thousands of miles to get from one asteroid to another.
Yet scientists are also looking closer to home. Determining the orbits and physical characteristics of objects that might impact Earth is critical to understanding the consequences of any such impact; and responding to an actual impact threat, if one is ever discovered. knows of no asteroid or comet currently on a collision course with Earth. But, to prepare for that scenario is developing the Double Asteroid Redirection Test or DART mission as the first demonstration of the kinetic impact technique that could be used to change the motion of a hazardous asteroid away from Earth.
Return Of The Blue Marble
The Deep Space Climate Observatory, a NOAA mission that carries NASA instruments, is providing a "new and complementary" view of Earth that is amazing scientists and lay people alike.
How To Land On A Comet
The European Space Agency's Rosetta spacecraft is about to attempt something "ridiculously difficult" - landing a probe on the surface of a speeding comet.
