Asteroids attack the Earth – myth, Asteroids attack the Earth – myth, speculation, or real danger?speculation, or real danger?

Ruslana Glazman, Sharet school/ASTROTOP, Netanya, IsraelRuslana Glazman, Sharet school/ASTROTOP, Netanya, Israel

Main questions in the project:

• How do we find asteroids in the sky?How do we find asteroids in the sky?• How do we estimate the orbit of discovered asteroids?How do we estimate the orbit of discovered asteroids?• What are asteroids and comets, and what is the What are asteroids and comets, and what is the

difference between them?difference between them?• Where do asteroids live? Do they live in the same area as Where do asteroids live? Do they live in the same area as

comets? How do they arrive here?comets? How do they arrive here?• What is the probability that an asteroid impact will What is the probability that an asteroid impact will

cause a disaster in the very near future? Is the cause a disaster in the very near future? Is the probability different depending on the amplitude of the probability different depending on the amplitude of the catastrophe (catastrophe (affecting a affecting a regionregion, , countrycountry, or the , or the whole whole planetplanet)?)?

• When was the last accident caused by asteroid or comet?When was the last accident caused by asteroid or comet?

Asteroids: How to find asteroids in the skyAsteroids: How to find asteroids in the sky??Data sources.Data sources.

•Method - permanent survey of a sky region by numerous groups in the world: NEO – Near Earth Objects search.

•Sources of my observational matter: Eudoxos Obs., Cephalonia, Greece: D-Space network of robotic telescope (1) ; Wise Obs., Mitspe Ramon, Israel, with David Polischuk (2)

(1)(1) (2)(2)

Asteroids: How do we find asteroids in the skyAsteroids: How do we find asteroids in the sky??Data analysis and identification of objects.Data analysis and identification of objects.

EUDOXUS (D-Space) – Asteroid 2017EUDOXUS (D-Space) – Asteroid 2017 Mitspe Ramon – NEO search Mitspe Ramon – NEO search ( 3 clicks)( 3 clicks)

How do we estimate the orbit of How do we estimate the orbit of discovered asteroids or cometsdiscovered asteroids or comets??

• Orbit is an ellipse• Parameters: a, b, i, ω, • Eccentricity:

• Aphelion = farthest distance = Ra,

• Perihelion = nearest distance = q = Rp

• Observing the asteroid over time in several positions gives the parameters of its orbit:

a

baε

22

α1,δ1,t1

α2,δ2,t2

α3,δ3,t3

………..

αn,δn,tn

abiωΩ

Ra

1 2 3

4

What are asteroids and cometsWhat are asteroids and comets,, and and what arewhat are differences between them? differences between them?

• Asteroids are stones (up to 1000 km). Asteroids have no tails. Meteorites are asteroids, falling to Earth. Their chemical contentss are carbonaceous chondrite (~93%), iron (4%).

• Comets are lumps of ice and frozen snow, covered by dark dirty spots of dust. The dark spots heat up when near the Sun, eject gas and dust, and form tails (two tails of dust and gas, separated by the pressure of solar wind)

Where do asteroids live? Do they Where do asteroids live? Do they live in the same area as comets?live in the same area as comets?

• We studied the distribution of all asteroids and cometsdistribution of all asteroids and comets by distance (a) , inclination to ecliptic (i), and eccentricity (ε)

(source: http://ssd.jpl.nasa.gov/?sb_elem, “Small-Body Orbital Elements”, catalog of Jet Propulsion Laboratory, NASA & CALTECH)

Examples: Asteroids Comets

Num Name a (AU) i (˚) e

2062 Aten 0.96 18.9 0.18

2100 Ra-Shalom 0.832 15.7 0.43

2340 Hathor 0.843 5.85 0.44

5381 Sekhmet 0.94 48.9 0.29

3554 Amun 0.97 23.3 0.28

5590 1990 VA 0.98 14.1 0.27

10563 Izhdubar 1.00 63.4 0.26

Num Name Epochq (AU)–

perihelion e i (˚)

1 P/Halley 46480 0.59 0.04162.

2

2 P/Encke 52560 0.34 0.1211.7

7

4 P/Faye 51320 1.66 0.14 9.05

6 P/d'Arrest 52320 1.35 0.1419.5

0

7 P/Pons-Winnecke 52640 1.26 0.15

22.28

8 P/Tuttle 49520 1.00 0.1754.6

9

9 P/Tempel 1 51920 1.50 0.1810.5

4

Where do asteroids live? Do they Where do asteroids live? Do they live in the same area as comets?live in the same area as comets?

Conclusions:Conclusions:1. Orbits of asteroids are localized in belts. Main belt - between

Mars and Jupiter in interval between 2 AU and3.5 AU. Secondary narrow belt is on Jupiter’s radius 5 AU – “Jupiter Trojans”. Scattered external belt is on the same distance as Pluto (Kuiper belt) – is Pluto one of them?

2. The asteroid orbits in the main belt are near ecliptic plane with low inclination (i<30) and are circle-like (low eccentricity).

3. The main belt is fragmented on its inner side and splits (possible result of resonance with gravitational disturbances of planets and proper instability of the asteroid’s belt).

4. Inner asteroids (Near Earth) are rare and are scattered randomly in space from Venus to the Main belt (where they are ejected from the Main Belt as a result of collisions).

5. Comet’s orbits are divided in two groups:– External comets up to thousands AU with high eccentricity

and high inclination (“hedgehog” distribution) – “Oort cloud”– Inner comets with perihelion > 4 AU with low eccentricity

and inclination (“disc” distribution) like the asteroids

These locations originate from a sequence of different stages in the Solar System’s origin from a primary gas-dust cloud to its present state

1. The law of Titius Bode explains the range of distances between the Sun and the planets:

•Explanation – resonance orbits, stable opposite to gravitational disturbances

N=- – Mercury, N=1 – Venus, N=2 – Earth

N=3 – Mars, N=5 –Jupiter, N=6 – Saturn

N=7 – Uranus, N=8 – Pluto, N=9 – Sedna

Main Asteroid Belt is in position n=4 exactly.

2. What is it – remnant from former planet’s explosion (Phaeton) or primary blocks for future planet building?

3. Now, astronomers reject Phaeton’s hypothesis (deficit summary mass, chemical content of meteorites, Jupiter influence).

Answer – asteroids and comets are “junk” of primary matter, remained after construction of the solar system.

Location of planets and asteroids and the law of Titius- Location of planets and asteroids and the law of Titius- BodeBode

1,2,3,... ,-n 2*3.04.0)( withAUD nn

What is the probability to have a disaster What is the probability to have a disaster from asteroid impact in the near future?from asteroid impact in the near future?

• Data for analysis comes from craters from past impacts. Source of data: database of asteroid craters identified on Earth:

http://www.unb.ca/passc/ImpactDatabase/CIDiameterSort2.htm

Asteroid impact and its sequencesAsteroid impact and its sequences

1. Velocity of asteroid in collision– 10-20 km/sec

2. Energy of explosion comes from the kinetic energy of a stopped asteroid = mV2/2. Correspondent energy of explosion convert to:

– Heating and evaporation of the asteroid/comet matter (chondrites / ice)

– Emission of overheated gas

– Shock wave and mass ejection into atmosphere and space

– Plastic deformation of the Earth matter with earth quakes and strong seismic waves

Distribution of impact cratersDistribution of impact craters by amplitude and ages by amplitude and ages

History of imacts (0 - 3 miliards years)

0

100

200

300

400

0 100 200 300 400 500

age in millions years

History of imacts (0-100 millions year)

0

10

20

30

40

50

0 10 20 30 40 50 60 70 80 90 100

age in millions years

dia

met

er i

n k

m

Planetary Catastrophe events (craters about 100 km - disaster region 10,000 km)

Power: Million Megaton TNT The largest crater - 800 km, 3 million years - Africa. Another example- 300 km, 65 million years, Chicxulub, Mexico -

Dinosaur’s killer (?)The last event - million years ago – Sweden – 130 kmMean time interval – 50-100 million years

Regional Catastrophe events (craters about 10 km, disaster region 100-1000 km)

Power: Million Megaton TNTThe last event – 13,000 years ago – IraqMean time interval –1-3 million years

Local Catastrophe events (craters 100 m - 1 km, disaster regions - ten kilometers)

Power: 100-1000 Megaton TNTThe last event – 100 years ago – Siberia, Tunguska (atmospheric

explosion with disaster region - 40 km)Mean time interval - about thousands years

History of imacts (0-10,000 years)

0.000

0.100

0.200

0.300

0.400

0.500

0.000 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008 0.009 0.010

age in millions years

diam

eter

in k

m

ConclusionsConclusions

•Asteroids and comets are stone and ice remnants of building junk from the period of the solar system construction.

•They are situated in belts and clouds.•A small part of them were scattered from their belt as a result

of a collision with another one and entered Earth orbit. •A small part of these guests has the probability to collide with

the Earth. •Possible impact may be from Planetary catastrophe (one in

tens millions of years), regional catastrophe (one in a few millions of years, and local catastrophe (one in a thousand – tens thousands of years)

•Last local event was in 1908 in empty region in the East Siberia, “Tunguska”. Region of destruction – 40 km. Now more then 30,000 people live in this region (!). Where can we find a place for the next impact with minimum negative sequences?

•Asteroid attack is real source of danger for a period of thousand years.

Who is waited to be the next visitor?Who is waited to be the next visitor?•NEONEO – Near Earth Objects program = permanent monitoring of the all sky by network of telescopes for timely discovery and identification of potentially dangerous asteroids/comets

•ApophisApophis = 2004 MN4: size 400 m, disasters region = 100 kilometers, expected probability of impact = 1/1000 years

It was discovered June 19, 2004 as a near-Earth asteroid that caused a brief period of concern in December 2004 because initial observations indicated a large probability that it would strike the Earth in 2029 (3%) = class 4 in Torino Scale of Impact hazards. Later (2006) orbit was calculated more exactly and possibility of impact in this transition was excluded (minimal distance about 30,000 km = just below the altitude of geosynchronous satellites (!!!), but without capture.

•Data of the next transition is April 13, 2029, Apophis will be observed by naked eye.

•Gravitational disturbances of Apophis orbit during transition near the Earth may shift it in new orbit with high probability of the impact. Next transition in 2036 may be dangerous.

?

?

Apophis in Mitspe Ramon observation [David Polischuk (2004)]

One from the possible scenarios of impact catastrophe from “Deep Impact” (God forbid !!!)