For those living in northern Australia, the second solar eclipse to take place in less than six months will take place around dawn on Friday.

The annular eclipse that will begin late Thursday will produce a “ring of fire” as the Moon covers all but the outer edges of the Sun.

In all, the Sun is nearly 400 times larger in diameter than the Moon; however, it is also almost exactly 400 times farther away, thus creating the illusion that the two are almost the same size.

However, the Moon’s apparent size is not steady - on April 27, for example it was at its closest point to Earth and should the eclipse have happened then, the Sun would have disappeared completely. As it is, on May 10, the Moon will appear to be 30 arcminutes in diameter, which in turn will leave roughly 5 percent of the Sun exposed.

Given that the frequency of a total solar eclipse for any given spot on Earth is once every 375 years, and every 224 years for annular eclipses, the occurrence of two solar eclipses in just a matter of months is rare: in all, the 20th century saw just 12 back-to-back solar eclipses, though that number jumps to 23 for the 21st century.

The last double feature to occur took place when a seven-minute total eclipse on July 22, 2009 was followed by an annular solar eclipse Jan. 15, 2010 over China.

The next to happen will take place on Dec. 26, 2019 and 21, 2020 - both of which will be annular eclipses - over the Middle East and as well as the Pacific Ocean.

As far as the United States goes, those living in south-central Texas will experience an annular eclipse on Oct. 14, 2023 followed by a total eclipse on April 3, 2024.