Top 10 space facts

Quick and bright "flare" in the sky. A Satellite flare (also called a Iridium flares ) is a phenomenon caused by man-made satellite where the sunlight is reflected back to Earth. This results in a quick and bright "flare." Some flares can be up to 20 times brighter than Venus. These can be very bright. So much so, that it can even be seen during the day.

Quasar. The four bright objects surrounding it are actually multiple images of a single quasar that lies far beyond the galaxy. The lens was named the Einstein Cross in honor of Albert Einstein, whose relativity theory predicted the phenomena decades before the first gravitational lens was observed in 1979.

A speed of light is always constant. The speed at which light propagates through transparent materials, such as glass or air, is less than c. However, this "slowing of the light" is only due to the fact of photos being absorbed and re-emitted after a slight delay between atoms. When a photon is emitted, it's speed is always c. In exotic materials like Bose–Einstein condensates near absolute zero, the effective speed of light may be only a few metres per second.

3 days. It took 1 minute of flight to reach Mach 1 and 12 minutes to enter Earth's orbit. After one and a half orbits, the third-stage engine pushed the spacecraft onto its three-day long travel to the Moon.

Quasars. A quasar is an extremely energetic source of radiation powered by accretion disc around galaxy's central supermassive black hole. Quasars were much more common in the early universe, as all known quasars are extremely distant.

Venus. If a planet's atmosphere contains radiatively active gases, they will radiate energy in all directions. Part of this radiation is directed towards the surface, warming it. The greenhouse effect on Venus is particularly large because its dense atmosphere consists mainly of carbon dioxide.

Magnetar. A magnetar is a type of neutron star with an extremely powerful magnetic field. The magnetic field decay powers the emission of high-energy electromagnetic radiation, particularly X-rays and gamma rays. As of March 2016, only 23 magnetars are known, with six more candidates awaiting confirmation.

Uranus is the seventh planet from the Sun. It has the coldest planetary atmosphere in the Solar System, with a minimum temperature of 49 K (−224 °C; −371 °F).

Uranus and Neptune. The diameters of Uranus and Neptune are respectively 25 362 km and 24 622 km - the difference is only 2.92%.

Black dwarf. A black dwarf is a theoretical stellar remnant, specifically a white dwarf that has cooled sufficiently that it no longer emits significant heat or light