In 1908, an asteroid crashed into a forest in Siberia. The force is estimated to have flattened 80 million trees with the heat from the burning rock being felt up to 35 miles away. The Tunguska event, as it became known, released energy equivalent to 185 Hiroshima bombs. Thankfully we've avoided such devastating impacts since, but that doesn't mean our planet is entirely safe.
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Today, an asteroid known as 2014 J025 will be the largest of its kind to come this close to Earth since 2004. Reports have described it as being "uncomfortably close," which has led to headlines suggesting a "rock the size of Gibraltar" is on a collision course with Earth. In reality, it’s 1.1 million miles away. Plus, Nasa has assured people this is no Deep Impact scenario.
While asteroid 2014 J025 is said to be coming ‘close’ to Earth, this is not to suggest it has any possibility of colliding with our planet, merely that its proximity is unique for a larger asteroid. Smaller asteroids come closer to earth at least several times a week and pose no threat.
But don't take our word for it. The Center for Near Earth Object Studies (CNEOS) at Nasa’s Jet propulsion laboratory has compiled a table detailing 'close Earth approaches' of all known near-Earth objects (NEOs). The official definition of an NEO is any comet or asteroid that has been "nudged by the gravitational attraction of nearby planets into orbits that allow them to enter the Earth’s vicinity."
CNEOS' software plots the approaches for all known NEOs and tabulates this data to organise it by time – essentially an Excel spreadsheet for asteroid recordings. This table is free for everyone and can be customised with different settings using filters.
For example, the table data can vary based on time, nominal distance and asteroid magnitude. Predictions for the future go up to a year, with near future predictions taking place within the next 60 days. These are measured in nominal lunar distance, which is a comparative measure of the distance between the Earth and the Moon. 2014 J025 has a nominal lunar distance of 4.57 – roughly quadruple the distance from the Earth to Moon. Having looked through the data, you may begin to feel a bit more optimistic about the possibility of asteroid impacts.
The closest predicted approach is scheduled for February 24, 2018. The space rock is not only going to come closer to Earth than 2014 J025 (with a nominal lunar distance of 3.65), but is also larger in terms of diameter.
2014 J025 is now visible, using the Arecibo Radio Telescope in Puerto Rico and can be seen in the above image. While the asteroid isn't close enough to cause a problem, astronomers believe it will be large enough to be visible in amateur telescopes, with a period of visibility beginning in the early morning hours of Wednesday and again on Wednesday night.
Of course, if you still want to entertain thoughts of near-impact scenarios, there's a section in the CNEOS graph for ‘uncertainties’.
The CNEOS states that “...the most important issue to remember when interpreting our NEO close-approach tables is the inherent uncertainty in each NEO orbit. This uncertainty is related to several parameters used in the orbit determination process including the number of observations (measurements), the time spanned by those observations (data arc), the quality of the observations (e.g. radar vs optical), and the geometry of the observations.”
It should also be noted that Earth close-approach data statistics can change – in the words of CNEOS “often by large amounts” – as new data becomes available.
This article was originally published by WIRED UK
