Astronomy questions

Acctually due to recent research, it appeared that abnormalities in gravitational fields astronomers have predicted that there might be a primordial black hole prevailing in the dust errees near the oort cloud. :SCIENCE FREAK

The Galilean moons are the four largest moons of Jupiter—Io, Europa, Ganymede, and Callisto. They were first seen by Galileo Galilei in December 1609 or January 1610, and recognized by him as satellites of Jupiter in March 1610.

The rings of Saturn are the planetary rings around the planet Saturn, which can be seen with a small telescope.The particles in the rings are made almost entirely of water ice, with just a small amount of dust and other chemicals. There are some gaps in the rings. The moon Pan causes the gap called the "Encke gap" in Saturn's A ring. The Cassini Division, discovered by Giovanni Domenico Cassini, is a gap between the A ring and the B ring. It is a product of orbital resonance.

Dark nebulae are clouds of dust which are simply blocking the light from whatever is behind. They are physically very similar to reflection nebulae; they look different only because of the geometry of the light source, the cloud and the Earth. Dark nebulae are also often seen in conjunction with reflection and emission nebulae. A typical diffuse nebula is a few hundred light-years across. (NGC 2264 shown; see also the Horsehead Nebula)

Voyager 1 is a space probe launched by NASA on September 5, 1977. Part of the Voyager program to study the outer Solar System, Voyager 1 was launched 16 days after its twin, Voyager 2. Having operated for 41 years, 7 months and 29 days as of May 4, 2019, the spacecraft still communicates with the Deep Space Network to receive routine commands and to transmit data to Earth. At a distance of 145 AU (21.7 billion km; 13.5 billion mi) from Earth as of February 22, 2019, it is the most distant from Earth of all known man-made objects.

Andromeda (mythology), a princess from Greek mythology. Andromeda (constellation), a region of the Earth's night sky. The Andromeda Galaxy, an astronomical object within the constellation.

The Pinwheel Galaxy ( M101) is a face-on spiral galaxy distanced 21 million light-years away from Earth in the constellation Ursa Major. M101 is a large galaxy, with a diameter of 170,000 light-years. By comparison, the Milky Way has a diameter of 258,000 light years. It has around a trillion stars, twice the number in the Milky Way. It has a disk mass on the order of 100 billion solar masses, along with a small central bulge of about 3 billion solar masses.

The Earth revolves around the sun, not the other way around.

Beta Cancri, also named Tarf is the brightest star in the zodiacal constellation of Cancer. It has an apparent visual magnitude of +3.5 and an absolute magnitude of −1.2. Based on parallax measurements obtained during the Hipparcos mission, it is approximately 290 light-years distant from the Sun.

Henry Cavendish, british physicist (1731-1810) was the first scientist to calculate mass of the Earth. Greater accuracy has not been achieved for nearly 100 years. He only made a mistake about 1% compared to today's calculations. Cavendish estimated the mass of the Earth to be 6 billion trillion tons. Modern calculations say about 5.9725 billion trillion tons. (5,97219×10^24 kg)