Let's Talk About Apohpis 2029

Not to topic drift in my own thread but why are scientists so worried about contaminating Mars when the Earth is constantly being contaminated with Mars rocks.....?

a reply to: lostbook

Because contaminating Mars could cause problems with the scientific studies being/going to be conducted.

a reply to: Gothmog

An asteroid , nowhere close to the size of Apophis , crashed into the Yucatan peninsula and damn near ended all life. I have heard the impact of that one was BILLIONS of times more powerful than some atomic bombs.

The dinosaur ending asteroid was estimated at 11 to 90 km across while Apophis is 3/10 of 1 km, around a thousand feet, so I'm just clarifying that Apophis is much smaller.

Still, I'd imagine it would change things globally and make for a very bad time for those outside of it's immediate obliteration area... meaning those nearest the impact would likely not even know it hit because they would be vaporized in milliseconds.

a reply to: Baddogma

Not extinction level. But definitely a bad day for many.

a reply to: Phage

Many asteroids are not solid cohesive bodies, but collections of ransom bits of rock/ice held together by gravitation
attraction ie the flying rubble or gravel pile

If such a body approaches too close to earth then gravitational and tidal forces could rip it apart and send fragments crashing down to earth

It doesn't take a very big piece to cause a lot of damage on earth

Meteor Crater in Arizona was caused by an iron meteor about 50 meters in size

The Chelyabinsk meteor in 2013 which exploded in the atmosphere was only about 20 meters

It detonated with force of about 500 kilotons

Even boulder size fragments can exploded in the atmosphere with force of a nuclear weapon

a reply to: firerescue

If such a body approaches too close to earth then gravitational and tidal forces could rip it apart and send fragments crashing down to earth

No. They would continue on their original orbit. If the original object was not going to impact, neither would the fragments.

You are referring to the Roche limit, by the way, and the rest of what you said is quite accurate.

originally posted by: Gothmog

originally posted by: cmdrkeenkid
a reply to: lostbook

The asteroid would have negligible impact on the Earth by flying by.

Even if it did impact, the damage, while devastating, would be limited regionally.

An asteroid , nowhere close to the size of Apophis , crashed into the Yucatan peninsula and damn near ended all life. I have heard the impact of that one was BILLIONS of times more powerful than some atomic bombs.

Good Grief...

Well, you are right it was no where near the size of Apophis. It was much much larger. The Chicxulub impactor according to its wiki entry was between 11 and 81 kilometres in diameter, that's kilometres. That is somewhat larger than 370 meters. Apophis would make a big splash but wouldn't end civilization.

originally posted by: MazMaric
So what would happen if it hit the moon?

Looking at the size of some of the craters on the moon already, I'd guess the moon would be fine from something of Apophis size. Be an awesome show from down here though.

originally posted by: Phage
a reply to: ArMaP

The Earth's gravity effect on Apophis may be enough to make it change slightly it's trajectory, so they will probably have to remake their calculations for the next passes

Earth's gravity (and that of the Moon and other planets) is taken into account. There will be slight variation because there are very small influences which cannot be dealt with, but not much. That is why they are confident in saying that the asteroid will not be a threat for at least 100 years, that's more than 100 orbits.

I'm also wondering about Gravity Wells and if NASA has already taken these into account.....? Gravity Wells could also change it's path and send it right into Earth. On the flip-side, a Gravity Well could also send it farther away from Earth.

a reply to: lostbook

Yes, I am really sure. Yes, the damage would be regionally devastating, not globally.

a reply to: lostbook

Not from this size of impactor. Information comes from high school physics. We have a rough idea of the mass and composition, we know the velocity. The rest can be figured out from there roughly on the back of a napkin.

If you really want to have some fun with it, however, I'd direct you to the Impact Effects Calculator.

At its largest Apophis is about 450 meters long. It is most likely composed of porous rock, with an assumed density of 2600 kg/m^3. The most likely impact velocity would be 17 km/s at an angle of 45 degrees. The most likely place of impact would be the oceans, which overall have an average depth of about 3700 meters.

So plugging in those numbers, and let's give you a modest 500 km distance from the impact.

At the impact site there would be quite the devastating release of energy at about 4000 MT. For comparison, Tsar Bomba, the largest nuclear weapon tested, was about 60 MT. It is estimated that an impact of this size occurs about once every 100k years.

As the distance involved puts the impact over the horizon, there would be no thermal radiation. There would be seismic effects, with an earthquake of about 3.6 magnitude reaching you about a minute and a half after the impact. No ejecta would reach your location. The air blast, with a peak overpressure of about 0.02 bars, would reach you nearly 30 minutes post impact as a 4.6 m/s breeze and be as loud as heavy traffic. This could crack or shatter single paned windows.

The largest threat would arrive nearly an hour later in the form of a 10 meter tsunami. This would be devastating, and for a comparison you can look up videos of the 2011 Japanese tsunami.

a reply to: cmdrkeenkid

Thanks for this. A tsunami from an ocean impact is another concern but i see you addressed it.

a reply to: lostbook

Well, then let's say the strike was in the middle of the North Pacific. Pretty good chances, as it's the largest area of water in the Northern Hemisphere. So call it around 32.32 N 174.42 W.

That's about 4000 km from Sendai, 4700 km from San Francisco, 7900 km Auckland. Why these cities? Other than being coastal cities, it was a completely arbitrary decision.

Other than those distances, all other data remains the same.

None of those three locations would see a fireball, there would be no seismic effects, and no ejecta would reach the cities.

At Sendai, the overpressure blast wave would come as a 0.5 m/s breeze and be heard at about the volume of a quiet office setting. A tsunami would arrive over seven hours later with a height of about 1.3 meters. San Francisco would be very similar for the overpressure wave and tsunami, only with the timing being slightly later. Auckland would have the overpressure wave reach even later, with slightly less pressure and not as audible. The power of the tsunami would also be even more diminished, arriving nearly 14.5 hours after impact and with a nominal height of 0.64 meters.

This would be pretty much a worst case scenario outcome of an impact from Apophis (aside from a direct impact to a population center, of course).

a reply to: cmdrkeenkid

Thanks. It kinda ruins the doomporn aspect of Apophis but good to know anyway. Phage tried to warn me. Lol

So Jupiter or the Sun won't be saving our asse's this time from a burning snake or skydog this time.

Apophis is an LL Chondrite. A stony asteroid structurally weak as chondrites go, having almost 20% iron, but all locked up in iron oxide. Chelyabinsk was an LL Chondrite. It detonated relatively high in the atmosphere, but caused some very minor damage due to the shock wave. it was only 20 meters in diameter. The Tanguska object is suspected of being an LL Chondrite, and was around 200 meters across. It also came in at a low angle and detonated, knocking down about 800 Sq miles of forest.

If Apophis detonated airburst style like the Chelyabinsk or Tunguska event, the fireball and resulting shock waves would most certainly totally destroy the town of Chelyabinsk and everything 50 miles around it, however the effects would not be Global Earth changing.

Most chondritics will detonate when hitting the denser part of Earth atmosphere as the shock tears the stony matrix apart, even the big ones. They can certainly make craters however, if they fail to completely detonate and they still have cosmic velocity when they hit Earth.

It is the big Irons that we really have to worry about. They have such mass and structural integrity, that they usually blow right through the atmosphere at high angles of attack. At low angles, they have actually held together enough for the atmosphere to slow them down so they fall at terminal velocity. Hoba, Cape York and Willamette are examples of that.

FYI

99942 Apophis, Discovered 19 June 2004
Near-Earth Asteroid

99942 Apophis is a near-Earth asteroid with a diameter of 370 metres that caused a brief period of concern in December 2004 when initial observations indicated a probability up to 2.7% that it would hit Earth on April 13, 2029. Additional observations provided improved predictions that eliminated the possibility of an impact on Earth in 2029. However, unti…
Wikipedia
iconWikipedia

~~~~~~~~~~~~~~~~~~~~~~~~~~~~



i do recall the early tracking info which stated the astroid had a 7 year orbit and that orbit would place the asteroid Above the Earth plane orbit on One /Pass... then below the Earth plane orbit on the Apophis second orbit pass

As a result of this orbit by the Asteroid, the Apophis (Chaos) spacerock is 'witnessed' by the the whole population of Earth (north hemisphere and south hemisphere populations) as required by in detailed Prophecies

(note: the orbit pattern of Apophis has probably been tracked better since the 2004 research, and thereby eliminates Apophis as the biblical 'wormwood' or 'chaos dragon' celestial mountain that falls to Earth during the end-times era of 7 years...


i posted on the over-under orbit passes by Apophis, years ago on some thread, that would take too much digging
there's a religion associated group, 'skywatch' that has since created a foggy mystique about Apophis as an end-times messenger to the believers on Earth ?? too much heavens gate woo-woo ??

originally posted by: Phage
a reply to: lostbook

Because contaminating Mars could cause problems with the scientific studies being/going to be conducted.

Since the Earth is contaminated with rock(s) from Mars then if Mars gets contamination from Earth, is it really contamination? In a sense, Mars is getting back what it's given to Earth, right?
I think I know what you're gonna say which is why i didn't pose this question before but I wanna hear it anyway...........