2018: Highlights in Space

Our sun: a ball of superhot gas

A big idol for energy researchers

The sun is basically a huge nuclear fusion reactor. At its core, pressure and temperature are so high that hydrogen atoms merge together to form helium atoms. This process releases huge amounts of energy. One thimble of sun material generates as much energy as burning thousand metric tons of coal does.

Our sun: a ball of superhot gas

100 times bigger than Earth

Seen from Earth, the sun doesn't seem big - it is just a bright spot in the sky. But it does have a radius of about 700,000 kilometres (435,000 miles). Its core is 15 million degree Celsius (27 million degree Fahrenheit). Temperatures on the sun's surface still reach 5500 degree Celsius (10,000 degree Fahrenheit).

Our sun: a ball of superhot gas

One in a billion

All stars in our universe glow because they generate energy deep down inside. Our sun is just like other billlions of stars scattered across the universe. In comparison with other stars, our sun is of medium size. Some stars are a hundred times bigger, others are just a tenth of the sun's size.

Our sun: a ball of superhot gas

Restless on the outside

The sun's surface is seething away. Hot and brightly glowing material ascends from the sun's inside, cools and sinks down again, appearing much darker. Our sun is the only star in the universe so close to Earth that astronomers can observe in such detail.

Our sun: a ball of superhot gas

Amazing sunspots

Sometimes big dark spots appear on the sun's surface staying for about a month. Even before the birth of Christ, humans already knew of those spots, and Galileo Galilei later recorded their appearance in writing. But for a long time people were mystified where those spots came from. Now we know the answer: they're areas with a particularly strong magnetic field.

Our sun: a ball of superhot gas

Dangerous storms

When the sun is very active, geomagnetic storms develop. It's when the sun catapults a particularly high number of charged particles into space. Those particles can hit and destroy satellites. They might also disturb electric power substations on Earth and even lead to power breakdowns.

Our sun: a ball of superhot gas

When the sky glows

This is another, much more beautiful effect of geomagnetic storms: an aurora, also called polar light. It occurs when charged particles of the sun hit the Earth's atmosphere. The frequency of how often we may enjoy this spectacle depends on the solar cycle. Every eleven years the sun is particularly active - that's when many geomagnetic storms and auroras can be observed.

Our sun: a ball of superhot gas

Please remember!

Never watch a solar eclipse without protecting your eyes. Even when the moon partly covers the sun, it is still extremely bright. Without sun protection you risk damaging your eyes - the retina can completely burn up. Fortunately, there are special eclipse glasses for such an event. They even look stylish, don't they?

Author: Alexandra Hostert

Passing through Saturn's rings: Cassini's last mission

Understanding the birth of planets

"No spacecraft has ever flown through this unique region," NASA administrator Thomas Zurbuchen said. "The information we'll gather from Cassini's daring final loops will improve our understanding of how giant planets and planetary systems are born. It's truly discovery in action until the very end."

Passing through Saturn's rings: Cassini's last mission

Fear of destructive particles

There's a gap of roughly 2,400 kilometers (1,490 miles) between gas giant Saturn and his rings. "Based on our models we expect this gap to be free of particles that would be big enough to do damage to our spacecraft," NASA project manager Earl Maize said. "There's definitely some things we don't know - but that's one of the reasons we're doing risky research like this at the end of the mission."

Passing through Saturn's rings: Cassini's last mission

Giant rose

Cassini has delivered spectacular pictures over the last 20 years. This image taken by the spacecraft shows Saturn's rotating storm clouds over the planet's north pole. Measurements have shown that the vortex has a diameter of 2,000 kilometers (1243 miles). The clouds in it are whipped around by the wind with a speed of up to 540 kilometers per hour (335 miles per hour).

Passing through Saturn's rings: Cassini's last mission

It's a small world

You can hardly tell it's there, but the arrow in this wide angle shot taken by Cassini marks our Earth - a tiny dot because the picture was taken from very, very far away. The distance between the spacecraft and Earth was roughly 1.44 billion kilometers. Saturn and its rings can be seen in the foreground.

Passing through Saturn's rings: Cassini's last mission

Pac-Man moons

From hot to cold: The colors show the unusual temperature patterns on Saturn's Mimas and Thetys moons. The data for this image was captured by the spacecraft's infrared camera.

Passing through Saturn's rings: Cassini's last mission

Life away from Earth?

Cassini has also collected data from Saturn moon Enceladus. Experts believe there are water molecules on the icy satellite. Researchers see this as proof that energy is created on Enceladus. This means that life on the satellite would theoretically be possible.

Passing through Saturn's rings: Cassini's last mission

Methane lakes

Also among Cassini's spectacular discoveries: the liquid methane lakes on Titan. Saturn's largest moon was discovered in 1655 by Dutch astronomer Christiaan Huygens. It's still interesting to researchers today: Cassini spent more than ten years around Titan.

Passing through Saturn's rings: Cassini's last mission

Cloud river

This view, composed of images taken by Cassini's wide-angle camera, is reminiscent of a large river. The images actually show clouds in Saturn's northern hemisphere. The final picture was made using a combination of spectral filters sensitive to infrared light.

Passing through Saturn's rings: Cassini's last mission

The end is nigh

If things go according to plan, Cassini's life will end on September 15. The 12,600-kilogramm spacecraft will start its controlled plunge toward Saturn 20 years after the mission began - and it will keep sending data to Earth until the very end. "Cassini will make some of its most amazing discoveries at the end of its long life," NASA researcher Linda Spilker said.

Author: Stephanie Höppner