In the first week of this month, the rare opportunity occurred to see a bright near-Earth asteroid known as ‘Florence,’ named after Florence Nightingale. The rock is almost three miles wide and passed around four and a half million miles from Earth on Friday 1st September. Classed as an Amor-group asteroid, it was discovered in 1981 and orbits the sun every two years. However, it will not approach the Earth again this closely until the year 2500.
The International Astronomical Union’s Minor Planet Centre classifies it as a “potentially hazardous” asteroid. However, orbital calculations have found there is little risk of collision with the Earth. Not for the next several centuries or even over the next millennia, there is only small chance of it threatening our plan in the distant future. This is good news, since every two thousand years or so an asteroid around the size of a football pitch collides with earth causing some serious damage. Every million or so years a large object comes along big enough to threaten the existence of Earth. Asteroids which do often come closer to our planet are estimated to be smaller; Florence is in fact the largest asteroid to pass by this closely since the start of the Nasa program to detect and track near Earth asteroids.
Since it has two moons, it’s classes as a ‘triple asteroid’ which is only the third example to be found near earth so far. With it being so close to the earth, even amateur astronomists were able to catch sight of it even with small telescopes and binoculars. If you find the best telescope within your budget, you will be set to see these interesting phenomenon as they occur. As these wonders only usually occur once in a lifetime, being able to see them with your own eyes is always incredibly special. So what does Florence look like? It has been described by Nasa as relatively spherical, with a ridge along its equator. At least one large crater has been observed too. Radar images taken of the asteroid confirmed that it rotates once every 2.4 hours- in fact, if it was spinning any faster it would completely come apart. Often when asteroids spin this fast is they rearrange into the shape of a spinning top, with a bulge along the equator.
Florence safely passed by the Earth on September 1, 2017- it was eighteen times the distance away than the earth is to the moon. Nevertheless, it’s the largest asteroid to pass this close to our planet for over a century, and an exciting night for both professional and amateur astrologists. If you missed this spectacular sight, keep an eye on websites like EarthSky. They will keep you up to date on what you’re able to see, and with some home equipment you will be able to catch the next incredible movement in the sky,
Did you catch sight of Florence? What’s the most incredible thing you have ever caught in the sky with a telescope or binoculars?