Top 10 astronomy factsAstronomy quiz
This is the aurora of Jupiter. What are the visible bright spots caused by?
Jupiter moons. Jupiter's moons, especially Io (spot on the left), are powerful sources of auroras on Jupiter. These arise from electric currents along field lines, generated by a dynamo mechanism due to the relative motion between the rotating planet and the moving moon.
What is the densest substance in the universe?
Neutron star. A neutron star is a stellar remnant of a supernova. Neutron stars are very small, but extremely dense - with a radius of only about 12–13 km (7 mi), they can have a mass of about two Suns.
What is larger in the sky: the Moon or the Sun? (By apparent size)
Sometimes the Moon, sometimes the Sun. The Moon's orbit is elliptical, and its apparent diameter varies by 10%. This is why both total eclipses (if the Moon is larger) and annular eclipses (if the Sun is larger) happen.
In which month is the Earth closest to the Sun?
In January. Earth's perihelion occurs around January 3, and the aphelion around July 4. The distance change is about 3.5%, which gives 6.9% increase in solar energy reaching the Earth at perihelion relative to aphelion. Since the southern hemisphere is tilted toward the perihelion, the southern hemisphere receives more energy from the Sun than does the northern over the course of a year.
What is the iridium flare?
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.
The closest star to the Sun is Proxima Centauri. In which direction we would need to look to see it in the night sky?
It is not visible at all. Proxima Centauri is a red dwarf and its average brightness is very low. That is why even though it is closest to the Sun, it was discovered not until in 1915.
The Einstein Cross seen in the picture is?
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.
Where do the names of Uranus moons (Ariel, Umbriel, Miranda, Titania, Oberon) come from?
Shakespeare's characters. William Herschel, Englishman, discoverer of Uranus and its major moons, was very patriotic for naming. He originally named Uranus as "George Star" to honour king of England, but the name was changed later.
This plaque, carried by Pioneer 10 and Pioneer 11 space probes, describes the location of the Sun. What are the points at the ends of the lines?
Pulsars. Each of the line includes binary encoding of pulsar frequency, so these can be easily recognized. The hydrogen spin-flip transition frequency is used as the unit of time (Hydrogen particle at the top of the image).
Which astronomical discovery was nicknamed 'Little Green Man'?
Pulsar. In 1967 Jocelyn Bell Burnell and Antony Hewish first observed pulses separated by 1.33 seconds, originated from the same location on the sky. It was not until a second pulsating source was discovered in a different part of the sky that the "LGM hypothesis" was entirely abandoned.