The US space agency Nasa recently announced that many of the Moon rocks brought back to Earth from two Apollo space missions have gone missing. They were given as gifts to the nations of the world. So what happened to them?

Sunsets on other planets appear different because of the differences in the distance of the planet from the Sun, as well as different atmospheric compositions. On Mars, the Sun appears only about two-thirds of the size that it appears in a sunset seen from Earth, because Mars is farther from the Sun than the Earth is. Although Mars lacks oxygen and nitrogen in the atmosphere, it is covered in red dust frequently hoisted into the atmosphere by fast but thin winds. At least some Martian days are capped by a sunset significantly longer and redder than typical on Earth. One study reported that for up to two hours after twilight, sunlight continued to reflect off Martian dust high in the atmosphere, casting a diffuse glow.

Asteroid Apophis can wipe us off the face of the Universe. It was named to honor the ancient Egyptian god of darkness and destruction. Discovered in 2004 asteroid’s size corresponds a skyscraper and weighs 20 million tons.

Whiz at speeds hundreds of times faster than a bullet, it is not a lower energy than all the nuclear weapons on the planet. Astronomers around know where it goes. According to their calculations, in April 2029 a huge boulder will fly in 34-36 thousands of miles from the Earth’s surface. This is close enough for the satellites in low Earth orbit, so this event is already dangerous. April 13, 2036 Apophis could collide with the Earth, said that date Professor of St. Petersburg State University, Leonid Sokolov. Fortunately, the likelihood that Apophis will fall on us, is extremely small, since the approach to our planet, will it break into pieces.

In spite of the risks, NASA hasn’t wasted any time in making plans to set up camp on the moon. The space agency is eyeing a parcel of land near the lunar south pole (where there’s constant daylight) for a moon base. In addition to a possible wealth of helium-3 or hydrogen fuel, the moon would be an ideal place to build a telescope or a launch pad to explore the solar system (with less gravity to overcome, the escape velocity for spaceships is significantly lower). Until the age of moon colonies finally arrives, however, you’ll just have to make do with a nightly view of Earth’s small, constant companion.

Sunspots are temporary phenomena on the photosphere of the Sun that appear visibly as dark spots compared to surrounding regions. They are caused by intense magnetic activity, which inhibits convection by an effect comparable to the eddy current brake, forming areas of reduced surface temperature. Like magnets, they also have two poles. Although they are at temperatures of roughly 3000–4500 K (2727–4227 °C), the contrast with the surrounding material at about 5,780 K leaves them clearly visible as dark spots, as the intensity of a heated black body (closely approximated by the photosphere) is a function of temperature to the fourth power. If the sunspot were isolated from the surrounding photosphere it would be brighter than an electric arc. Sunspots expand and contract as they move across the surface of the Sun and can be as large as 80,000 kilometers (50,000 mi) in diameter, making the larger ones visible from Earth without the aid of a telescope. They may also travel at relative speeds (“proper motions”) of a few hundred m/s when they first emerge onto the solar photosphere.

Planet Venus traced out this S shape in Earth’s sky during 2004. Following the second planet from the Sun in a series of 29 images recorded from April 3rd through August 7th (top right to bottom left) of that year, astronomer Tunc Tezel constructed this composite illustrating the wandering planet’s path against the background stars.

Earth’s moon shines brightly in our sky, but it is not the only satellite in our solar system. Experts estimate there are as many as 170 moons orbiting the eight planets of our section of the galaxy. A moon is defined as a satellite that orbits a planet. Moons are named after Roman and Greek gods and demigods — with colors and mystifying landscapes that match their fanciful namesakes. Here’s our look at some of the beautiful, bold and essentially unexplained moons of our solar system. Pictured here is a false color image from NASA of Saturn’s moon, Rhea. 

The Tunguska event, or Tunguska blast or Tunguska explosion, was an enormously powerful explosion that occurred near the Podkamennaya Tunguska River in what is now Krasnoyarsk Krai, Russia, at about 7:14 a.m. on June 30, 1908. The explosion is believed to have been caused by the air burst of a large meteoroid or comet fragment at an altitude of 5–10 kilometres (3–6 mi) above the Earth’s surface. Different studies have yielded varying estimates of the object’s size, with general agreement that it was a few tens of metres across. The number of scholarly publications on the problem of the Tunguska explosion since 1908 may be estimated at about 1,000 (mainly in Russian). Many scientists have participated in Tunguska studies, the best-known of them being Leonid Kulik, Yevgeny Krinov, Kirill Florensky, Nikolai Vladimirovich Vasiliev and Wilhelm Fast. Although the meteoroid or comet burst in the air rather than hitting the surface, this event is still referred to as an impact. The behaviour of meteorites in the Earth’s atmosphere was less well understood during the early decades of the 20th century. Due to this, as well as the paucity of relevant data resulting from Soviet secrecy during the Cold War, a great many other hypotheses for the Tunguska event have sprung up, none of which are accepted by the scientific community.

The Andromeda–Milky Way collision is a predicted galaxy collision that could possibly take place in approximately 3 to 5 billion years’ time between the two largest galaxies in the Local Group—the Andromeda Galaxy and the Milky Way, which contains Earth. Each galaxy contains over a hundred billion stars, which is 100 million trillion possible collisions. Nevertheless, the chance of even two stars colliding is negligible because of the huge distances between them. For example, the nearest star to the Sun is Proxima Centauri, about thirty million solar diameters away. If the sun were a ping-pong ball in Paris, the ping-pong-Proxima would be in Berlin and our galaxy would be 12 million miles wide—about a third of the distance to Mars. Stars are much denser near the galactic centers—the average separation is only 100 billion miles. But that is still a density of one ping-pong ball every two miles.

A giant patch of frozen water has been pictured nestled within an unnamed impact crater on Mars. The photographs were taken by the High Resolution Stereo Camera on board Mars Express, the European Space Agency probe which is exploring the planet.

An aurora is a natural light display in the sky particularly in the high latitude regions, caused by the collision of energetic charged particles with atoms in the high altitude atmosphere. The charged particles originate in the magnetosphere and solar wind and are directed by the Earth’s magnetic field into the atmosphere. Aurora is classified as diffuse or discrete aurora.

Stanley Winston was an American visual effects supervisor, makeup artist, and film director. He was best known for his work in the Terminator series, the Jurassic Park series, Aliens, the Predator series, Iron Man, Edward Scissorhands, and Avatar. He won four Academy Awards for his work. Winston, a frequent collaborator with director James Cameron, owned several effects studios, including Stan Winston Digital. The established areas of expertise for Winston were in makeup, puppets and practical effects, but he had recently expanded his studio to encompass digital effects as well.

Austrian skydiver Felix Baumgartner, pictured during a 25,000ft altitude test jump for Red Bull Stratos. He is renowned for the particularly dangerous nature of the stunts he has performed during his career. Baumgartner spent time in the Austrian military where he practiced parachute jumping, including training to land on small target zones.

Full moon is a lunar phase that occurs when the Moon is on the opposite side of the Earth from the Sun. More precisely, a full moon occurs when the geocentric apparent longitudes of the Sun and Moon differ by 180 degrees; the Moon is then in opposition with the Sun. Lunar eclipses can only occur at full moon, where the moon’s orbit allows it to pass through the earth’s shadow. Lunar eclipses do not occur every month because the moon sometimes passes above or below the earth’s shadow. The time interval between similar lunar phases - the synodic month - averages about 29.53 days. Therefore, in those lunar calendars in which each month begins on the new moon, the full moon falls on either the 14th or 15th of the lunar month. Because lunar months have a whole number of days, lunar months may be either 29 or 30 days long.

The late heavy bombardment is a period of time approximately 4.1 to 3.8 billion years ago (Ga) during which a large number of impact craters are believed to have formed on the Moon, and by inference on Earth, Mercury, Venus, and Mars as well. The evidence for this event comes primarily from the dating of lunar samples, which indicates that most impact melt rocks formed in this rather narrow interval of time. While many hypotheses have been put forth to explain a “spike” in the flux of either asteroidal or cometary materials to the inner solar system, no consensus yet exists as to its cause. The Nice model popular among planetary scientists postulates that the gas giant planets migrated in orbit at this time, causing objects in the asteroid belt and/or Kuiper belt to be put onto eccentric orbits that reached the terrestrial planets. Nevertheless, some argue that the lunar sample data do not require a cataclysmic cratering event near 3.9 Ga, and that the apparent clustering of impact melt ages near this time is an artifact of sampling material affected by a single large impact basin.