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You may have, or will soon hear about the asteroid 2004 MN4. What is significant about 2004 MN4 is that it has reached an all-time hazard level on the Palermo Scale, and the Torino scale .. two scales that measure the hazard rating of an asteroid.

The most sginificant event is the close encounter between Earth and 2004 MN4 on 2029-04-13 around 21:21 UTC. We currently estimate hit the Earth, it would impact at a speed of 12.6 km/sec. It would hit the Earth, it would impact at a speed of 12.6 km/sec. It would You may have, or will soon hear about the asteroid 2004 MN4. What is significant about 2004 MN4 is that it has reached an all-time hazard level on the Palermo Scale, and the Torino scale .. two scales that measure the hazard rating of an asteroid.

The most significant event is the close encounter between Earth and 2004 MN4 on 2029-04-13 around 21:21 UTC. We currently estimate that there is a 1.6% chance that 2004 MN4 will impact the Earth during that pass. This has given 2004 MN4 a hazard rating of 4 on the Torino Impact Hazard Scale. A 4 means:

A close encounter, with 1% or greater chance of a collision capable of causing regional devastation.

The highest previous was a 1.

2004 MN4 is also rated with a +1.02 on the Palermo Technical Impact Hazard Scale Torino Impact Hazard. No other object has every reached close to +1.0 before.

2004 MN4 appears to be an asteroid that is 420 meters in diameter. It has a mass of about 1.2e+11 kg. Models show that IF it were to hit the Earth, it would impact at a speed of 12.6 km/sec. It would take only 1.4 second to pass from the upper Stratosphere to the surface. The nearly 1/2 km wide asteroid would pass through Earth's atmosphere intact, and strike the surface with an equivalent explosive force of about 2200 Megatons of TNT. Such an impact would cause devastation on a continent sized scale.

All models are is solid agreement that 2004 MN4 has only a 1 in 63 chance of impacting the Earth. So there is a 98.4% chance that it will miss the Earth. On the other hand, no object of this significant size as posed such a known threat to Earth in recorded history. Nothing of even close to this size has ever impacted the Earth during recoded human history.

These models are based on 64 observations made by 10 different observatories over a span of 6 months. That is a long enough observation record confirmed by multiple skilled observers to take seriously.

I'll stress again that there is a 62 out of 63 chance that 2004 MN4 will miss the Earth in 2029-04-13. Even so, this object deserves careful watching. Stay tuned / watch this space for further details.

The 2003-EG16 asteroid had the top position in the current impact risks , but lost to to a new asteroid: 2003-EE16. A writeup of the 2003-EE16 asteroid should appear in this journal soon.

The 50 New observations over 4.6 days is a bit short to create an extremely accurate model.

Based on the new observations, we calculate the following information for 2003-EG16:

• Diameter: 579m (up from 544m)
• Mass: 2.6e11 kg (up from 2.2e11 kg)
• Impact speed (only IF it hits): 23.70 km/s (up from 23.53 km/s)
• Potential impact energy (only IF it hits): 18,000 Megatons (up from 14,000 Megatons)
• Torino impact hazard scale : 0 (no change)
• cumulative Palermo Scale : -2.41 (up from -2.42)
• close Earth approach paths in next 100 yrs: 22 (down from 96)
• Earth impact odds in the next 100 yrs: 1 in 714,000 (up from 1 in 769,000)

Based on the estimated size and mass: IF 2003-EG16 were to hit the Earth on land, its impact would result in sub-continent scale devastation. IF 2003-EG16 were to hit the Earth in the ocean, it would create a tsunami the size and speed of which have not been seen in recorded history. Such a tsunami would would inflict total devastation along adjoining coastlines and in some cases spread destruction far inland.

The impact speed, IF 2003-EG16 hits the earth remains on the higher end of the typical asteroid approach speed.

The odds of 2003-EG16 impacting Earth means that there is a 99.99986% chance the asteroid will miss the Earth.

We would not be surprised to see additional observations modify the orbit model and reduce the hazard level of this asteroid sometime in the future.

The 2003-EG16 asteroid has taken the top position in the current impact risks .

Because we only have 36 New observations over 2 days, the current orbit model should be considered highly speculative.

Based on the new observations, we calculate the following information for 2003-EG16:

• Diameter: 544m
• Mass: 2.2e11 kg
• Impact speed (only IF it hits): 23.53 km/s
• Potential impact energy (only IF it hits): 14,000 Megatons
• Torino impact hazard scale : 0
• cumulative Palermo Scale : -2.42
• close Earth approach paths in next 100 yrs: 96
• Earth impact odds in the next 100 yrs: 1 in 769,000

Based on the estimated size and mass: IF 2003-EG16 were to hit the Earth on land, its impact would result in sub-continent scale devastation. IF 2003-EG16 were to hit the Earth in the ocean, it would create a tsunami the size and speed of which have not been seen in recorded history. Such a tsunami would would inflict total devastation along adjoining coastlines and in some cases spread destruction far inland.

The impact speed, IF 2003-EG16 hits the earth remains on the higher end of the typical asteroid approach speed.

The odds of 2003-EG16 impacting Earth means that there is a 99.99987% chance the asteroid will miss the Earth. You should still plan to pay your taxes, go to work/look for work, and continue to wait for new South Park episodes. :-)

The asteroid known as 2003-CR20 has been removed from the current impact risks table. The orbit model has been refined by 149 observations to show that there is a nil chance of impact with the Earth in the next 100 years.

Long range models continue to show that both Venus and Mars will continue have close encounters with 2003-CR20 making close encounters with Earth beyond 2103 possible.

Good news!!! With 115 observations over almost 18 days, 2003-CR20 risk has been lowered to the point where is no longer has a Torino impact hazard scale of 1!

Based on the new observations, we calculate the following information for 2003-CR20:

• Diameter: 604m (up from 560m)
• Mass: 3.0e11 kg (up from 2.4e11 kg)
• Potential impact speed 25.10 km/sec (up from 24.85 km/sec)
• Potential impact energy(only IF it hits): 23,000 Megatons (up from 18,000 Megatons)
• Torino impact hazard scale : 0 (down from 1)
• cumulative Palermo Scale : -3.09 (down from -1.04)
• close Earth approach paths in next 100 yrs: 5 (down from 13)
• Earth impact odds in the next 100 yrs: 1 in 4,167,000 (down from 1 in 20,000)

There is a 99.999976% chance the asteroid will miss the Earth during the next 100 years.

The following is a table of the close Earth approaches by 2003-CR20 where Earth lies within the 5-sigma path. See my explination for the data in this table. The 5-sigma approaches as of the time of this Journal entry are:

1. 2031-09-20.56 1.04 +/-0.353 (Earth inside 3-sigma path)
2. 2043-09-20.19 0.29 +/-0.593 (Earth inside 1-sigma path)

The most significant close approaches have been marked in bold. The ''highest risk'' approach is 2043-09-20.19 0.29 +/-0.593 with only a 1 in 111,111,000 chance that 2003-CR20 will impact the Earth on that pass.

The 2003-CR20 orbit model has become much better for the Earth. It has dropped to 4th place on the current impact risks table. As of 2003-Feb-28 21:00 UTC the refined model's Torino impact hazard scale had dropped to the -2's, but we didn't have time to port a Journal update. As more data comes in, 2003-CR29 risk seems to be declining further.

It has been shown that 2003-CR20 had an encounter with Venus on 1960-01-23.33 with a pass somewhere under the 1,000,000 km range. This encounter may have been the event to have nudged 2003-CR20 into its current high-risk orbit. This high-risk orbit will not last long as an close encounter with Mars in 2096-01-07.15 and another with Venus in 2097-11-12.28 will move 2003-CR20's orbit further away from Earth's path.

2003-CR20 seems to be a wild slingshot ride among Venus, Earth and Mars. Only time will tell where it ends up, but for the next 100 years it is VERY unlikely that it will hit the Earth. No doubt 2003-CR20 will be watched on future trips near Earth. New data may shed new light in the long term nature of its orbit. But the next few years we seem to be safe from that asteroid.

We hope you have enjoyed watching these updates as much as we enjoyed the challenge of modeling this very unusual orbit.

P.S. There is no change is status for 1997-XR2. That asteroid remains as the only non-zero Torino impact hazard scale object.