Our planet Earth: Close Encounters With Other Heavenly Bodies
Our wonderful planet earth is one of the trillions of heavenly bodies in this vast universe. According to many experts, the age of our earth is 4.54 billion years. It has survived many close encounters with other heavenly bodies (like asteroids) over these years.
Before we proceed, it is important familiarize ourselves with the terms potentially hazardous object (PHO), near earth object (NEO), observation arc and astronomical unit (AU).
A potentially hazardous object is a near-earth asteroid or a comet with an orbit such that the object has the potential to make close approaches to the earth; the potentially hazardous object is of a size large enough to cause significant damage in the event of impact.
A near earth object (NEO) is a solar system object whose orbit brings it into proximity with our planet. NEOs have a closest approach to the sun of less than 1.3 AU.
Observation arc is the length of the path traced by the observations of the object.
1 AU = 149,597,871 km.
Here is a brief overview of earth’s close encounters:
Hope none of them will hit our planet in the future!
(152680) 1998 KJ9 is a potentially hazardous object. It is well-known for its close approach (around 144,000 miles) to the earth on December 31, 1914. According to experts, this asteroid is one of the largest objects (diameter of around 500 m) known to have come inside moon’s orbit.
This near earth asteroid passed the earth on December 27, 1976. It was 580,000 miles from the earth. This potentially hazardous object has a diameter of around 660 feet and an observation arc of two years.
EM26, an asteroid as large as three football fields, flew past the earth at a staggering speed of 27,000 mph. It was around 885 feet in diameter. This occurred on a Monday, February 18, 2014. The asteroid came close to about two million miles from causing serious damage to our earth.
Two suns in the sky?
On February 15, 2013, an asteroid weighing around 10 tons entered earth’s atmosphere over Russia with a speed of around 40,000 mph. It became a bright meteor over the southern Ural region.
Its light was brighter than that of the sun. People also felt intense heat because of its presence. Due to its high velocity, the meteor exploded over Chelyabinsk Oblast, at a height of around 18 miles.
This energy released from the explosion was around 20 times more than that released from the atomic bomb detonated at Hiroshima. The explosion generated a powerful shockwave. Thousands of buildings were damaged; around 1,200 people were injured.
This near earth asteroid passed the earth on August 27, 1969. It was around 860,000 miles. This potentially hazardous object has a well determined orbit and was discovered on September 8, 1999. It is approximately 5 km in diameter.
2014 DX110 is an asteroid which passed less than one lunar distance from the earth on March 5, 2014. One lunar distance is 238,900 miles. At 9 pm UT, on March 5, 2014, this asteroid was 216,000 miles from earth. 2014 DX110 is roughly 16-131 feet in diameter.
OMG! What is that streaking across the sky?
In 1972, a bright meteor bounced off earth’s atmosphere. It was like a skipping stone bouncing off the surface of a pond. Many people (from Utah, USA to Alberta, Canada) witnessed this amazing event, which lasted several seconds.
This earth grazing meteor was clearly visible in daylight, and was photographed streaking above TetonMountains behind Jackson Lake, Wyoming, USA. According to experts, this earth grazer might be as big as a small truck. It might have created an impressive air burst had it struck our earth more directly.
This near-earth asteroid passed the earth on December 3, 2011. It was around 210,000 miles from earth; that is less than one lunar distance. 2011 XC2 is around 200-460 feet in diameter.
This near-earth asteroid passed the earth on August 30, 1925. It was around 210,000 miles. According to experts, this potentially hazardous object (diameter or around 2,400 feet) shows a 1 in 9,300 chance of impacting our planet earth in 2049.
Comet Hartley 2
This small periodic comet has an orbital period of 6.46 years. It passed within around 11,000,000 miles of earth on October 20, 2010. Hartley 2 was visible throughout the North American continent during early November around midnight.
This asteroid is around 850 feet in diameter. It passed the earth on January 29, 2008, at a distance of 344,370 miles. It is considered to be a potentially hazardous asteroid (PHA). It has an observation arc of about three years.
This asteroid passed earth on October 30, 1937 at about two times the distance of the moon. It is named after Hermes, son of Zeus and Maia. Hermes was a messenger of the gods.
This potentially hazardous asteroid is around 350 m in diameter. On November 8, 2011, it passed our planet earth. It was around 201,900 miles. During this passage, the asteroid was studied with radar using Goldstone, Arecibo, the Very Long Baseline Array, and the Green Bank Telescope.
This near-earth asteroid passed earth at a distance of 140,000 miles. It is considered a potentially hazardous object and is one of the largest objects known to have passed inside the orbit of the moon.
This small asteroid was discovered on March 31, 1989, nine days after its closest approach to the earth. It is named after the Greek demigod of medicine and healing. According to experts, this asteroid will pass 1,100,000 miles from the earth on March 24, 2051.
Curious to know who is behind all this? Watch this! LOL!!
This near-earth asteroid is classified as a potentially hazardous asteroid due to its size and due to the proximity of its orbit to earth. 2004 XP14 passed the earth on July 3, 2006 at a distance of 268,700 miles. Even though its exact size is not known, experts estimate it to be between 300 and 900 meters in diameter.
This near earth asteroid passed our planet earth on December 11, 2013. It was 472,000 miles from the earth; that is around two lunar distances. Experts estimate its diameter to be between 30 to 70 meters.
This near earth asteroid passed the earth on June 14, 2012. It was 5.4 million km from the earth. This potentially hazardous object is around 1 km in diameter. However, according to experts it has zero chance of impacting the earth for at least another 750 years.
Our amazing planet earth is providing us a place to exist. It is nurturing us day after day. It is our duty to protect it. Many scientists are working towards developing a system that would enable them to redirect heavenly bodies that threaten to collide with the earth. We will hope that such a system will soon be in place.
What we need to watch out for: Predicted encounters
Distance from the earth
April 13, 2019
170 to 370 meters
January 2, 2101
(308635) 2005 YU55
360 plus or minus 40
November 8, 2075
(153814) 2001 WN5
700 to 1,500 meters
June 26, 2028
85640 1998 OX4
170 to 370 meters
January 22, 2148
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