Tell me about the universe.

2013 April 19 This photo taken by Hubble Telescope was released to celebrate the 23 years of orbiting telescope. It shows a part of Orion's sky. In this amazing infrared image, the Horsehead Nebula (also known as Barnard 33) rises like a giant hippocampus from the turbulent flow of gas and dust.

Magellan Venus Probe 1990- 1994 has formed this photo centered on the North Pole of Venus after years of radar detection. This composite image is color-coded to show the altitude.

On Saturn, clouds are hexagonal. This hexagonal cloud structure was first discovered by Voyager in the 1980s. In 20 12, Cassini once again discovered this hexagonal cloud and took photos. No one knows why this region of Saturn forms this geometry.

The halo of this galaxy is the result of the collision between the wheel galaxy and another galaxy about 1 100 million years ago. The first ripple is a blue outer ring, and the yellow-orange "yolk" of Easter eggs is a combination of visible light and infrared light emitted by the second ripple. The neon dot and the green spiral in the background are two other galaxies.

What will the night sky look like from an exoplanet? No one knows the exact answer, but the painting created by this artist has given scientists great imagination. This cluster is a dwarf galaxy, consisting of 99% dark matter and 1% normal matter. Dark matter is evenly distributed in dwarf galaxies, which is contrary to scientists' expectations. Scientists initially thought that dark matter would gather at the center of these galaxies like peach stones.

In this picture, cold air is injected into the forming galaxy, and the "arm" of gas provides raw materials for the star formation of the new galaxy. No one has seen this process in real life. This version of galaxy formation is based on a theoretical scenario of numerical simulation.

The European Space Agency's Mars Express sent back an image of a slender crater in the southern hemisphere of Mars. The researchers said that it is located in the southern Huygens Basin and may have been formed by a series of asteroids hitting Mars at a small angle. This nameless depression is about 78 kilometers long and 2 kilometers deep. In the picture, purple represents the lowest area and gray represents the highest area.

The picture shows the pre-collision of galaxies. Millions of years later, these two spiral galaxies will merge, just as the Milky Way and Andromeda will merge in billions of years.

The photos of the back of the moon taken by the lunar reconnaissance orbiter have an orbital height of only 50 kilometers.

This photo taken by Hubble Space Telescope shows NGC 1275 galaxy, which is located in the center of perseus cluster. Red linear filaments consist of cold gas suspended in a magnetic field.

Mariner's Valley is the largest canyon in the solar system. It is a narrow and wide strip drawn on the surface of Mars. The Grand Canyon is 3000 kilometers long, 600 kilometers wide and 8 kilometers deep. In contrast, the largest canyon on earth is 800 kilometers long, 30 kilometers wide and 1.8 kilometers deep. The origin of Mariner's Valley is still unknown. One of the main hypotheses is that it began with a crack when Mars cooled billions of years ago.