ASTEROIDS

Wikipedia e Nasa (C)

HISTORY: The first astronomer to propose the existence of asteroids was Keplero (1571 -1630) that in his Mysterium Cosmographicum he wrote "Inter Jovem et Martem interposui planetam", in how much in base his ideas of perfect geometry of the solar system missed a body. However passed many years, up to 1772, when the hypothesis returned to the footlights with the Law of Titius-Bode dn=0 ,4+0,3x2^n. according to which missed a planet for n =3. Meanwhile in that time an eclectic Hungarian baron, Franz Xavier von Zach was devoted to a search deepened of this object systematically fathoming the whole sky. But it was alone by chance that an abbot teatino of the Valtellina, in strength near the observatory in Palermo, that on January 1 1801 discovered by chance a mobile star in the Taurus not brought in his catalogs. Initially exchanged for comet owed retract him seen its slow motion and the aspect without head of hair. He osserved for 41 days, and after a coarse respect of the orbit it called Ceres Ferdinandea. None of his contemporaries however, Bode, Zach, Oriani and others, had succeeded to define an orbit precise; succeeded in the intent the young and genial Karl Gauss, that had just invented a mathematical system to so precise that sufficent 3 observations for determining the type of conic. Was found again in fact to end year to less half degree from the calculated position, a record for that time! The greatest semiasse of 2.77 A.U. it was almost exactly that anticipated from the formula of Titius-Bode.

Finally in the 1809 Gauss pubblic his Theoria motus corporum coelestium.

Other surprise March 28 th 1802 when Wilhelm Olbers announced the discovery of a new object, Pallade, very similar as orbital characteristics to Cerere. It was hard to probably believe us but the same Olbers suggested that the objects of that zone had to be very numerous, and he began an observe campaign. On September 1 1804 arrived Juno, three years later Vesta. All defined planetoid came, while Herschel proposed asteroids, or rather "to form of star." The enthusiasms were cooled up to 1845 when the 5 asteroid was discovered Astraea. Two years later Hebe. In 1868 they had reached 100, the double after ten years and the triple after twenty. When in the 1891 Max Wolf applied the photo to the astronomy was another revolution and the discoveries they quickly increased. Today CCDs have subsequently improved these searches also allowing the not professionals to make innumerable discoveries. Big contributions also arrive daily from the projects Spacewatch, NEAT, LINEAR and LONEOS.

All the discoveries and observations are notified to the Smaller Planet Center of Cambridge that catalogs them and it names them. Reading the underlying chart is noticed as their number is in exponential growth; only considering the bodies of superior ransom to the km they esteem him 1.5-2 million asteroids, a number that climbs giddy to decrease of diameter of the asteroids. And difficulty becomes also to give him a name: exhausted those of the classical mythology him passed to that German, northern, Indian, to names of famous characters of the past and living, then to the pure imagination; however a special errand adequately occupies.

FORMATION: After the initial hypothesis of a thick planet mysteriously disintegrated him after the orbit of Mars, taken foot the theory of the missed planet or rather a planet whose formation, to the aggregation of planetesimi, it was prevented by the continuous perturbations of the thick planet giant Jupiter. During million of years the asteroids with very irregular orbits have been expelled, while those remained ones is distributed on varied orbits, often gathered in families, and however subjects to frequent mutual clashes.

DEFINITION : An asteroid or small planet or planetoid, is a small object, mainly rocky, of composition very similar to that of the planets, but of form almost never spherical and very small. They are mainly found in the principal belt, between Mars and Jupiter, and you/they can be divided in families (you see under). You thinks that they are the rest of the disk protoplanetary that milliard of years ago has brought to the formation of all the other planets and whose residual they have not succeeded in joining.

The orbits are very various, both as semi-axis that as inclination, and also the forms and the dimensions are innumerable; they prevail the small bodies in how much probably rests of collisions of great asteroids on unstable orbits.

POSITION : There are mainly 7 zones of the Solar System where the asteroids are found :

• Principal belt : between 2 e 4 U.A. between Mars and Jupiter, a large belt with some gaps; that empty spaces are dutiy to strong gravitational interaction of Jupiter where the asteroids isn’t cucceed to enters, because they were in orbital resonance.
• The Troianis: they are found in the points lagrangiani of Jupiter, to ±60° from its orbit, in a very stable orbital area and in equilibrium. Also Mars was discovered that it possesses about ten Troiani, and even Neptune has one of it. The Centaurs: also says transgioviani, they orbit to great distance from Jupiter. The founder was Chirone, discovered in 1977, of over 100 km of diameter. Probably they are asteroids that have risked to be expelled by the solar system.
• The Transnettunianis: are found over Neptune, to them it turns divided in Belt of Edgeworth-Kuiper, diffused disk and cloud of Oort.The first asteroids of the belt of Kuiper were open in 1992 from David Jewitt and Jane Luu.

• The Cubewanis, rocky asteroids of the belt of Kuiper that it orbits around the Sun of more then 41 A.U. They have also called classical objects of the belt of Kuiper. The name has origin from the first object open trans-nettuniano, (15760) 1992 QB1s. The following objects were called "QB1-os", or cubewanos, translating the initials in English. The term subsequently entered the common use in the different languages.

• The Plutinis, asteroids that introduce an orbital resonance 2:3 with Neptune. The prototype of the family naturally is Pluto, the first object with a similar orbit to be open. The plutinis constitute the part most inside of the belt of Edgeworth-Kuiper; around a quarter of the present objects in this region of the solar system they are plutini.
• The Twotinis, asteroids of the belt of Edgeworth-Kuiper in orbital resonance 2:1 with the planet Neptune. The name, derived by the English language, given by the terms two and plutino (or a planetoid in resonance 3:2 with Neptune). The known plutinis are more numerous of the twotinis.

CLASSIFICATION : The asteroids are classified in base to the ghostly type, or rather to their chemical composition. There are 10 classes:

• Asteroids type C - 75% of the known asteroids. The C is for "carbonaceus." They are very dark (inclusive albedo among 0,02 and 0,08, middly 0,03) and they have approximately the same composition of the Sun except the volatile elements. Their ghosts relatively have blue colors, and they are very flat and without evident structures.
• Asteroids type S - 17% of the known asteroids. The S is for stony. They are relatively bright objects (albedo 0,15-0,25). Their metallic (mainly silicati of nickel, iron and magnesium, olivina and pirosseno) composition. The ghost of these asteroids has a strong red component.
• Asteroids type M – 7%. The M is for "metallic." They are very bright asteroids (albedo 0,1-0,18), composed of almost pure nickel-iron. Sideritis are said.
• Asteroids type E – The E is for enstatite a silicato of magnesium of the group of the pirossenis. They have elevated albedo, 0,4.
• Asteroids type R – The R is for red, with obvious reference to their color. They are constituted by ferrous silicati and they have low albedo, 0,16.
• Asteroids type U – The U is for undefinited. Hybrid asteroids from the characteristics not defined.
• Asteroids type F – Asteroids typical of the external region of the principal belt, with low albedo and inclining color to the blue one.
• Asteroids type P – Asteroids with low albedo, reddish color, always in the external zone of the belt.
• Asteroids type D – Very dark asteroids (albedo 0,03) and red, typically belonging to Troiani.
• Asteroids type A – Composed asteroids mainly from olivina.

TYPOLOGY : The asteroids are also classified in base to the orbit.

• Asteroids type Aten – They belong to the Near-Earth and they possess an orbit with great semiaxys inferior to an astronomic unit. The name of the group derives from that of asteroid Aten, the first object of this type to be discovered January 7 th 1976 by Eleanor Helin.

• Asteroids type Apollo – They belong to the Near-Earth and they possess an orbit with greatest semyaxis of an astronomic unity. The name of the group derives from that some asteroid Apollo, the first object of this type to be discovered April 24 th 1932 by Karl Reinmuth.
• Asteroids type Amor – They belong to the Near-Earth and they possess an orbit that externally grazes that of the Earth. The great majority of the asteroids Amor intersects the orbit of Mars.

1. The asteroids Amor type T have inclusive orbit between that terrestrial and that Martian (between 1,000 and 1,523 A.U.). The belonging bodies to this subgroup, altogether less than a fifth of the general population, shows eccentricit orbital redoubts.
2. The asteroids Amor type II have inclusive orbit between that of Mars and the principal belt (between 1,523 and 2,12 A.U.) ; about the thied of the general population of the group it belongs to this category, included the prototype Amor. The orbital eccentricity of these asteroids are moderate; their orbits necessarily intersect that of Mars
3. The asteroids Amor type III, that alone constitute almost the 50% of the general population of the group, have orbits with great semyaxis between 2,12 and 3,57 A.U.; he treats, substantially, of asteroids of the principal belt that, fortheway of the elevated orbital eccentricity, unusually show a perielio next to the terrestrial orbit.
4. The few asteroids Amor IV are characterized by a middle distance by the greatest Sun of that of the principal belt; they have orbits with great semyaxis that overcomes the 3,57 UAs, and they necessarily intersect the orbit of Jupiter.

• Asteroids type Centauri – Family of asteroids with an orbit around the Sun understood between those of Jupiter and Neptune. Often their orbit isn’t stable and they can be expuls from the solar system in following the gravitational interaction with the greatest planets.
• Asteroids type NEA – Family of asteroids with an orbit near to that of the Earth. Some of them constitute a danger perch their orbits they intersect that terrestrial. The asteroids Near-Earth known are around 1000 , with dimensions up to around 32 km (1036 Ganymeds). The total number could be of some about ten thousand, of which more than 2000 with superior diameter to a kilometer.

ALBEDO : The curves of light show that the asteroids often have a lengthened form and irregular, and so much more grows its ellipticity so much it grows the variation of luminosity also reaching 1-2 magnitudes. But important factor of this pure variation the albedo, said also reflecting power or reflectivity, a numerical value given by the relationship between the quantity of reflected solar radiation and that receipt. It varies between 0 and 1, but in practice the most frequent values are around 0.02 and 0.5, with an average of 0.15. they are therefore very dark objects.

DIMENSION : this is the list of the asteroids of great dimensions (within the orbit of Neptune)

Number	Name	Diameter (km)	Middle distance from the Sun A.U.	Dyiscovery date	Discoverer
1	Cerere	975×909	2,766	1 january 1801	Giuseppe Piazzi
4	Vesta	578x560x458	2,361	29 march 1807	Heinrich Wilhelm Matthäus Olbers
2	Pallade	570×525×500	2,773	28 march 1802	Heinrich Wilhelm Matthäus Olbers
10	Igea	407,1	3,137	12 april 1849	Annibale De Gasparis
511	Davida	326,1	3,167	30 may 1903	Raymond Smith Dugan
704	Interamnia	316,6	3.063	2 october 1910	Vincenzo Cerulli
52	Europa	302,5	3,100	4 february 1858	Hermann Mayer Salomon Goldschmidt
624	Ettore	370×195	5,222	10 february 1907	August Kopff
3	Giunone	290×240×190	2,668	1 september 1804	Karl Ludwig Harding
87	Silvia	384×264×232	3,490	16 may 1866	Norman Robert Pogson
31	Eufrosine	255,9	3,150	1 september 1854	James Ferguson
15	Eunomia	255,3	2,646	29 july 1851	Annibale De Gasparis
16	Psiche	253,2	2,921	17 march 1852	Annibale De Gasparis
65	Cibele	237,3	3,434	8 march 1861	Ernst Wilhelm Leberecht Tempel
324	Bamberga	229,4	2,683	25 february 1892	Johann Palisa
451	Patientia	225,0	3,060	4 december 1899	Auguste Charlois
532	Ercolina	225*	2,772	20 april 1904	Max Wolf
107	Camilla	222,6	3,478	17 november 1868	Norman Robert Pogson
48	Dori	221,8	3,109	19 september 1857	Hermann Mayer Salomon Goldschmidt
45	Eugenia	214,6	2,720	27 june 1857	Hermann Mayer Salomon Goldschmidt
29	Anfitrite	212,2	2,556	1 march 1854	Albert Marth
121	Ermione	209	3,446	12 may 1872	James Craig Watson
423	Diotima	208,8	3,066	7 december 1896	Auguste Charlois
13	Egeria	217×196	2,576	2 november 1850	Annibale De Gasparis
94	Aurora	204,9	3,165	6 september 1867	James Craig Watson
88	Tisbe	200,6	2,768	15 june 1866	Christian Heinrich Friedrich Peters
24	Temi	198*	3,130	5 april 1853	Annibale De Gasparis

Apart this list, the greatest part of the asteroids have a very small diameter, and as such to the telescope they appear as of the bright dots of which is impossible to esteem the diameter. A good method for to obviate the drawback is to use the stellar occultations, the phenomenon according to which an asteroid occasionally transits before to a star hiding it. In base to the duration of the event and the position of the observatories is possible to reconstruct the form and the middle dimensions of the hiding body, but only if it overcomes the 30 km. More observations can also esteem the form of the asteroid. Methods improve of respect they are the radiometry and the polarimetry, in degree to calculate the albedo, and to which tied the dimension. The first method founds him on the infrared issue, the second on the polarization of the reflected solar light.

The asteroids with superior diameter to 200 km are 30, those with diameter between 100 and 200 km are about 200. Approximately the number is tied to the law D^-a, with D in km and a inclusive between 2.5 and 3.3. Insofar the number of asteroids of the order of the 100 meters overcomes the milliard.

The form of the asteroids is generally oblong and extending to that of an ellipsoid to three aces, expecially the greatest asteroid. I am often craterized and with superficial irregolarity.

MASS AND DENSITY : despite their boundless number, the whole population of the asteroids weigh arrives as soon as to 0,0007 times the mass of the Earth. Their density is very varying and it passes by 1 g / cm³ to 8 g / cm³, as from the water to the iron. Typical values are between 2 and 3,5. For comparison the Earth 5.5 g / cm³. For this value the asteroids possess a low velocity of disperses, and on the small bodies to a man a leap would be enough for entering orbit or to lose absolutely in the space!

ORBITS : the orbits of the asteroids are very various, with eccentricity assembled between the values 0,05 and 0,3, and with inclinations orbital averages from 0 to 35. The 95% of them assemble him in a belt between 2.1 and 3.6 A.U., with exclusion of some zones said gaps for the resonances with Jupiter.

PARTICULAR ASTEROIDS : asteroids with various characteristics.

Number	Name	Diameter (km)	Note
5	Astrea	119,1	The first asteroid to be individualized 38 years after the first four.
31	Eufrosine	255,9	The first asteroid to be individualized from Nord America.
45	Eugenia	214,6	The first asteroid to be named with a person’s name, the queen Eugenia of Montijo, wife of Napoleone III (also if remain doubtfoul on name’s origin of 12 Victoria).
61	Danaë	82,0	The first asteroid to has a type not ascii in the name.
62	Erato	95,4	The first asteroid discovered from 2 persons..
67	Asia	58,1	The first asteroid discovered from Asia.
85	Io	154,8	Asteroid with the shortest name, 2 types. (follow: 954 Li, 1714 Sy, 2705 Wu, 3271 Ul, 6498 Ko, e 22260 Ur)
87	Silvia	384×264×232	The first triple asteroidal sistem. The 2 orbiting moons around to Silvia have been discovered 18 feb 2001 and 10 aug 2005
90	Antiope	110 + 110	Double asteroid with the two components ugual and near; it’s binary type has been discovered with adaptive opticals.
92	Undina	126,4	Born 8 million years ago, in follow to the most catastrophic impact among asteroid of the last 100 millions years.
139	Juewa	156,6	The first asteroid discovered in China by James Craig Watson. The name was choice by chinese official.
216	Cleopatra	217×94	Metallic asteroid with a shape to “dog bone”.
243	Ida	56×24×21	The first binary asteroid confirmed. Photo to near distance of Galileo probe.
	Dactyl	1,4	Moon of 243 Ida, the first asteroid’s satellite confirmed.
288	Glauke	32	Rotation’s period exceptionally slow, about 1200 hours (2 months)
323	Brucia	36	The first asteroid discovered by astrophotography
333	Badenia	78	The first asteroid to receive a provisional designation (1892A)
433	Eros	13×13×33	The first Near-Earth asteroid, the second NEA in greatness order.
490	Veritas	115	Born 8 million years ago, in follow to the most catastrophic impact among asteroid of the last 100 millions years.
624	Ettore	370×195	The biggest troian asteroid of Jupiter.
719	Albert	2,4	Last numbered asteroid to be lose and subsequently to be recovered.
944	Hidalgo		Asteroid of then principal belt with the most long orbital period.
1125	Cina		First asteroid with a state’s name.
1566	Icaro		Asteroid Apollo; its perihelium is the more near to the Sun than Mercury.
1743	Schmidt	17	The first asteroid to be discovered thanks to collaboration of three people.
2060	Chirone	170	The first Centauro to be discovered and the first to receive the disignate of comet
3200	Fetonte	5	The first asteroid discovered from the space. It’s the source of Geminidi.

SPATIAL MISSIONS : select asteroids for spatial missions

Numero	Nome	Diametro (km)	Missione
1	Cerere	959×933	Target of Dawn probe (2015).
4	Vesta	468	Target of Dawn probe (2011).
21	Lutetia	96	Target of Rosetta probe (2010).
140	Siwa		Target leaves of Rosetta probe.
243	Ida	56×24×21	It was visited by Galileo probe in 1993.
253	Matilde	66×48×46	Ii was visited by NEAR Shoemaker probe in 1997.
433	Eros	13×13×33	The first asteroid studied from orbit and the first landing on an asteroid (NEAR Shoemaker, 2000-01)
951	Gaspra	19×12×11	The first asteroidi it was visited by a probe (Galileo,1991)
1620	Geographos	5.1×1.8	It was the target of Clementine probe,
2530	Shipka		Target leaves of Rosetta probe.
2685	Masursky	15-20	Observed by Cassini probe.
2703	Rodari		Target leaves of Rosetta probe.
2867	Šteins		Target of Rosetta probe (2008).
3352	McAuliffe	02-mag	Target leaves of Deep Space 1 probe.
3840	Mimistrobell		Target leaves of Rosetta probe.
4660	Nereo		Target leaves of NEAP probe and Target leaves of Hayabusa mission.
4979	Otawara	5.5	Target leaves of Rosetta probe.
5535	Annefrank	4	Target of Stardust probe.
9969	Braille	2.2×0.6	Visited by Deep Space 1 probe in 1999.
25143	Itokawa	~1	Target of Hayabusa probe with a return of samples

NUMBER : list of the total number of the discovered asteroids, with a number and with a name

DATE	TOTAL	NUMBERD	NAMED
2007 JUN 30	377328	160015	13805
2007 APR. 2	371670	155368	13722
2006 APR. 13	329777	129436	13040
2005 APR. 7	277090	99906	12268
2004 APR. 15	243682	79084	11242
2003 MAY 1	215930	58092	10573
2002 APR. 27	175753	39462	9213
2001 APR. 8	121595	24599	8334
2000 APR. 18	72201	14788	7369
1999 APR. 2	49757	10448	6533
1998 APR. 11	38629	8603	5898
1997 APR. 22	34264	7625	5544
1996 APR. 4	30331	6938	5127
1995 APR. 15	27766	6353	4820

RECORD APPROACH : list of the asteroids that in past has been near to less than 0.026 A.U.s.To., equal to the distance Earth-Moon (384400 km).

Distance Date (TT) Provisional name H

(UA)

0.000086 2004 Mar. 31.65 2004 FU162 28.7

0.000226 2004 Dec. 19.86 2004 YD5 29.3

0.000328 2004 Mar. 18.92 2004 FH 25.7

0.000560 2005 Nov. 26.02 2005 WN3 29.9

0.000564 2003 Sep. 27.96 2003 SQ222 30.1

0.00072 1994 Dec. 9.79 1994 XM1 28.0

0.000785 2006 Feb. 23.29 2006 DD1 26.5

0.000788 2002 Dec. 11.35 2002 XV90 25.0

0.000802 2002 Jun. 14.09 2002 MN 23.4

0.000820 2005 Oct. 10.18 2005 TK50 29.1

0.000963 2005 Mar. 18.91 2005 FN 26.9

0.000991 2003 Dec. 6.79 2003 XJ7 25.7

0.00099 1993 May 20.86 1993 KA2 29.0

0.00107 2006 Ago. 31.90 2006 QM111 30.5

0.00108 2003 Sep. 19.24 2003 SW130 29.2

0.00111 2004 Jul. 16.21 2004 OD4 26.7

0.00113 1994 Mar. 15.72 1994 ES1 28.5

0.00114 1991 Jan. 18.72 1991 BA 28.5

0.00120 2007 Mar. 11.07 2007 EH 27.7

0.00122 2006 Oct. 21.11 2006 UE64 27.9

0.00125 2005 Oct. 30.01 2005 UW5 27.0

0.00137 2006 Jan. 29.44 2006 BF56 29.5

0.00146 2005 Dec. 5.47 2005 XA8 26.1

0.00147 2007 Apr. 24.86 2007 HB15 27.8

0.00155 2006 Feb. 24.17 2006 DM63 26.7

0.00160 2004 Mar. 27.85 2004 FY15 26.1

0.00177 2007 Mar. 13.23 2007 EK 29.6

0.00177 2005 Jan. 13.43 2005 BS1 27.4

0.00179 2006 Oct. 30.70 2006 UJ185 27.9

0.00181 2006 Mar. 8.64 2006 EC 26.6

0.00185 2004 Apr. 18.01 2004 HE 26.7

0.00188 2003 Oct. 12.07 2003 UM3 28.1

0.00188 2006 Jul. 23.45 2006 OK3 27.0

0.00198 2004 Oct. 24.73 2004 UH1 28.1

0.00205 2007 Feb. 21.41 2007 DN41 26.7

0.00205++ 2001 Jan. 15.85 2001 BA16 25.8

0.00216 2006 Nov. 16.65 2006 WP1 28.2

0.00217 2007 Jan. 18.12 2007 BD 26.0

0.00217 2004 Dec. 16.80 2004 XB45 26.6

0.00221 2003 Apr. 29.27 2003 HW10 27.2

0.00222 2007 Feb. 11.53 2007 CC27 26.8

0.00222 2006 Nov. 20.24 2006 WX29 27.9

0.00225 2006 Jan. 28.31 2006 BV39 29.2

0.00233 2006 Nov. 21.42 2006 WV 27.2

0.00246 2004 Sep. 21.98 2004 ST26 26.3

0.00246 2004 Sep. 13.65 2004 RU109 26.5

0.00259 2007 Jan. 19.64 2007 BB 27.6

0.00282 2002 Mar. 31.15 2002 GQ 26.3

0.00289+ 1995 Mar. 27.15 1995 FF 26.5

Note :

+ Approach to the Moon,0.0013 U.A. , 27 Mar 1995

++ Approach to the Moon,0.00053 U.A. , 15.8 Jan 2001

CONVERSION BETWEEN PARAMETER H AND DIAMETER : if it takes the left value of H the diameter is in km, if it takes the right value is in meters.

H Albedo H

0.50 0.25 0.05

-2.0 4700 - 6700 - 14900 13.0

-1.5 3700 - 5300 - 11800 13.5

-1.0 3000 - 4200 - 9400 14.0

-0.5 2400 - 3300 - 7500 14.5

0.0 1900 - 2600 - 5900 15.0

0.5 1500 - 2100 - 4700 15.5

1.0 1200 - 1700 - 3700 16.0

1.5 940 - 1300 - 3000 16.5

2.0 750 - 1050 - 2400 17.0

2.5 590 - 840 - 1900 17.5

3.0 470 - 670 - 1500 18.0

3.5 370 - 530 - 1200 18.5

4.0 300 - 420 - 940 19.0

4.5 240 - 330 - 740 19.5

5.0 190 - 260 - 590 20.0

5.5 150 - 210 - 470 20.5

6.0 120 - 170 - 370 21.0

6.5 95 - 130 - 300 21.5

7.0 75 - 110 - 240 22.0

7.5 60 - 85 - 190 22.5

8.0 45 - 65 - 150 23.0

8.5 40 - 50 - 120 23.5

9.0 30 - 40 - 95 24.0

9.5 25 - 35 - 75 24.5

10.0 19 - 25 - 60 25.0

10.5 15 - 20 - 50 25.5

11.0 12 - 17 - 37 26.0

11.5 9 - 13 - 30 26.5

12.0 7 - 11 - 24 27.0

12.5 6 - 8 - 19 27.5

13.0 5 - 7 - 15 28.0

13.5 4 - 5 - 12 28.5

14.0 3 - 4 - 9 29.0

14.5 2 - 3 - 7 29.5

15.0 2 - 3 - 6 30.0

15.5 1 - 2 - 5 30.5

16.0 1 - 2 - 4 31.0

16.5 1 - 1 - 3 31.5

17.0 1 - 1 - 2 32.0

17.5 1 - 1 - 2 32.5

RESONANCES : In the celestial mechanics, the orbital resonance happens when two orbiting bodies have such periods of revolution that their relationship expressible in fractions of small integers. Then the two bodies practice, each other, a regulate gravitational influence. This phenomenon can to stabilize the orbits and to protect her from gravitational perturbations. The gaps of Kirkwood are gaps in the distribution of the asteroids of the principal belt according to the greatest semiaxys. They correspond to types of orbits in orbital resonance with Jupiter.

Gaps of Kirkwood

To notice that there are little asteroids with a greatest semiaxys next to the 2,5 AU or a 3,95 year-old orbital period, equal to a thirt of that of Jupiter (called for this orbital resonance 1:3). Other orbital resonances correspond to the orbital periods whose lengths are simple fractions of that of Jupiter. The resonances more weak they conduct only to an emptying of the asteroids, while the woodpeckers in the histogram are often have to the presence of a prominent family of asteroids.

The gaps were noticed for the first time by Daniel Kirkwood in 1857, that said correctly as the gaps were caused by the orbital resonances with the great planet.

The gaps of Kirkwood are situated to an orbital middle distance of:

1.9 AU (resonance 2:9)

2.06 AU (resonance 1:4)

2.25 AU (resonance 2:7)

2.5 AU (resonance 1:3) – in it orbit the asteroid’s family Alinda.

2.706 AU (resonance 3:8)

2.82 AU (resonance 2:5)

2.95 AU (resonance 3:7)

3.27 AU (resonance 1:2) - in it orbit the asteroid’s family Alinda.

3.7 AU (resonance 3:5)

The gaps more meaningful they correspond to the resonances 1:3, 2:5, 3:7 e 1:2.

PROVISIONAL DESIGNATION : In attends him of a definitive name, the Minor Planet Center it attributes to a just discovery asteroid a code formed by the 4 figures of the year of discovery, followed by a white space, from two capital letters and eventually from a number.

The first letter points out the two weeks in which happened the discovery, according to the following table:

JAN 01-15 A APR 01-15 G JUL 01-15 N OCT 01-15 T

JAN 16-31 B APR 16-30 H JUL 16-31 O OCT 16-31 U

FEB 01-15 C MAY 01-15 J AGO 01-15 P NOV 01-15 V

FEB 16-28 D MAY 16-31 K AGO 16-31 Q NOV 16-30 W

MAR 01-15 E JUN 01-15 L SEP 01-15 R DEC 01-15 X

MAR 15-31 F JUN 16-30 M SEP 16-30 S DEC 16-31 Y

The second letter points out the number of discovery in the two weeks: a points that the first discovery asteroid in that period, B the second etc. The letter “I” is jumped (don't confuse “I” with the number one), then H points the eight discovery and J the ninth up to Z that points the twenty-fifth discovery asteroid in the two weeks pointed by the first letter. For the following discoveries the number is added, departing from 1. The 26 discovery asteroid between 16 and the 30 June of the 2000 it’ll have the designation 2000 MA1s, the 27 MB1, the 50 MZ1, the 51 MA2, the 5000 MZ199 etc.

DOUBLE ASTEROIDS : Some asteroids have an own moon (satellite) that orbits around.

Asteroid	Category	Diameter (km) or dimension	Satellite	Diameter (km) or dimension	Distance (km)
22 Calliope	Main belt	(231.4×175.3×146.1)	(22) I Linus	38±6	1,065±8
45 Eugenia	Main belt	214.6±4.2	(45) I Petit-Prince	12.7±0.8	1,184±12
87 Silvia	Main belt	(384×264×232)	(87) I Romolo	18±4	1,356±5
			(87) II Remo	7±2	706±5
90 Antiope	Main belt	110±16	S/2000 (90) 1	110±16	170±1
107 Camilla	Main belt	222.6±17.1 (325×223×139)	S/2001 (107) 1	9±1	1,235±16
121 Hermione	Main belt	209.0±4.7 (265×180×180)	S/2002 (121) 1, LaFayette (nome provvisorio)	18	794.7±2.1
130 Elettra	Main belt	182.3±11.8	S/2003 (130) 1	4	1,252±30
243 Ida	Main belt	(59.8×25.4×18.6)	(243) I Dactyl	(1.6×1.4×1.2)	108
283 Emma	Main belt	148.1±4.6	S/2003 (283) 1	12	596±3
379 Huenna	Main belt	92.3±1.7	S/2003 (379) 1	7	3,400±11
617 Patroclo	Troian asteroid	105	(617) I Menezio	95	610
762 Pulcova	Main belt	137.1±3.2	S/2000 (762) 1	20	810
809 Lundia	Main belt	?	S/2005 (809) 1	?	?
854 Frostia	Main belt	15?	S/2004 (854) 1	?	~50
1089 Tama	Main belt	12.9	S/2003 (1089) 1	9	20
1313 Berna	Main belt	11	S/2004 (1313) 1	11	35
1509 Esclangona	Main belt	12	S/2003 (1509) 1	4	140
1862 Apollo	Apollo asteroid	1.7	S/2005 (1862) 1	0.08	3
3671 Dioniso	Near-Earth Asteroid	1.5	S/1997 (3671) 1	0.4	2.2
3749 Balam	Main belt	7	S/2002 (3749) 1	1.5	310±20
(26308) 1998 SM165	Trans-Nettunian object	420?	S/2001 (26308) 1	170?	11,310±110
(47171) 1999 TC36	Plutino	590?	S/2001 (47171) 1	250?	7,640±460
(66391) 1999 KW4	Near-Earth Asteroid	1.2	S/2001 (66391) 1	0.36	2.6
69230 Hermes	Apollo Asteroid	~0.4	S/2003 (69230) 1	~0.4	~1

TORINO SCALE : The Torino Scale uses numbers from 0 to 10, and points the possibility of collision (zero means instead that the object doesn't have any possibility of impacts with the Earth, while 10 mean the certain collision). An important parameter the dimension of the NEO: zero means that the small too object to cross the atmosphere and to arrive to Earth; 10 point instead that the object is enough great to determine a global climatic disaster.

The Turin staircases it uses numbers and colors :

White - it means "events without consequences": in this case the object mancher the Earth, or too much small to succeed in crossing the atmosphere. White therefore it corresponds to zero.

Green - it means "events to be held under careful control ": it deals with objects that have possibilit of very low collision. And' advisable to follow its orbital evolution to try to redefine the possibilits of collision with following measurements. Green corresponds to 1.

Yellow - "events that arouse worry": the objects have a tall probabilit of impact, essential to follow its orbital evolution and to finish up the orbit. Yellow corresponds to 2 - meeting brought closer with unlikely collision; to 3: meeting brought closer with with probabilit > 1% of impact, that would provoke destructions on the local plan; and to 4, meeting brought closer with probabilit > 1% of impact that would provoke destruction on the regional plan.

Orange - "threatening Events": it deals with meetings brought closer with great objects enough to provoke destruction on the regional plan and even global. A redefinition of the orbit in this crucial case. Orange corresponds therefore to: 5 - meeting brought closer with meaningful threat of collision that would provoke devastation on the regional plan; 6 - meeting brought closer with meaningful threat of collision able to provoke a global (planetary) devastation; 7 - meeting brought closer with a very meaningful threat of global catastrophe.

Red - "certain Collision": it deals with objects whose collision with the certain Earth, great enough to provoke, in correspondence with the numbers: : 8 - local destructions; 9 - regional destructions; 10 - global climatic effects.

ORBITAL PARAMETERS (ATEN) :

Designazione e nome Prov. Des. q Q EMoid H Epoca M Peri. Node Incl. e a Opps.

2007 ML24 0.500 1.039 0.01058 19.0 20070410 104.1 200.2 282.9 34.0 0.350 0.770 ( 3d)

2007 MC4 0.803 1.141 0.12432 21.1 20070410 75.5 358.3 109.4 19.2 0.174 0.972 ( 25d)

2007 MF 0.935 1.034 0.01645 26.2 20070410 124.0 348.0 85.7 17.5 0.050 0.984 ( 2d)

2007 LB15 0.568 1.309 0.00663 19.5 20070410 28.9 237.3 262.9 25.2 0.395 0.938 ( 41d)

2007 LL 0.810 1.152 0.08422 20.4 20070410 81.5 211.5 247.3 10.0 0.174 0.981 ( 38d)

2007 JB21 0.890 1.105 0.00088 25.4 20070410 62.1 256.9 228.1 13.4 0.108 0.997 ( 7d)

2007 HA 0.473 1.311 0.01513 20.4 20070410 269.7 133.2 205.8 33.0 0.470 0.892 ( 6d)

2007 FN3 0.729 1.257 0.14686 23.3 20070410 266.3 138.1 177.6 48.4 0.266 0.993 ( 1d)

2007 EP88 0.096 1.579 0.14205 18.5 20070410 148.8 46.9 328.7 20.8 0.886 0.837 ( 61d)

2007 EB26 0.119 0.980 0.11303 19.6 20070410 310.8 237.4 62.3 8.4 0.783 0.550 ( 6d)

2007 EX 0.508 1.235 0.12416 17.0 20070410 151.6 78.9 297.5 18.7 0.418 0.871 (135d)

2007 EG 0.478 1.032 0.00878 24.6 20070410 253.1 168.8 166.5 3.1 0.367 0.755 ( 6d)

2007 EF 0.484 1.157 0.02481 20.8 20070410 139.4 226.0 158.4 21.7 0.410 0.821 ( 38d)

2007 EC 0.745 1.109 0.02423 22.2 20070410 205.9 45.8 308.0 5.8 0.196 0.927 ( 51d)

2007 DB61 0.516 1.107 0.01358 23.6 20070410 177.7 209.0 159.5 5.4 0.364 0.812 ( 16d)

2007 DM8 0.625 1.351 0.01540 26.2 20070410 124.6 61.4 332.6 7.5 0.367 0.988 ( 4d)

2007 DE8 0.601 1.146 0.05098 23.3 20070410 296.6 327.0 327.1 13.2 0.312 0.874 ( 1d)

2007 DD 0.874 1.106 0.00592 25.8 20070410 138.9 76.5 331.5 2.5 0.117 0.990 ( 15d)

2007 CA27 0.568 1.163 0.13260 21.1 20070410 247.4 200.0 123.0 30.0 0.344 0.866 ( 28d)

2007 CT26 0.524 1.186 0.00242 23.4 20070410 168.3 44.4 321.8 2.9 0.387 0.855 ( 24d)

2007 CM26 0.773 1.112 0.06157 25.1 20070410 279.3 152.3 142.7 7.1 0.180 0.942 ( 11d)

2007 CS5 0.811 1.150 0.00067 24.6 20070410 151.0 261.7 125.7 0.7 0.173 0.980 ( 16d)

2007 BG29 0.554 1.111 0.08687 18.0 20070410 318.3 245.1 61.1 18.5 0.335 0.832 ( 35d)

2007 BU7 0.627 1.263 0.01016 24.1 20070410 165.6 241.6 120.3 21.1 0.337 0.945 ( 7d)

2007 BG 0.526 1.047 0.05198 19.6 20070410 277.5 133.3 168.4 12.7 0.331 0.787 ( 71d)

2007 BD 0.481 0.986 0.00257 25.4 20070410 310.0 359.1 297.6 9.3 0.345 0.733 ( 4d)

2007 BB 0.800 1.064 0.00151 27.8 20070410 342.0 301.7 298.0 3.5 0.142 0.932 ( 2d)

2007 AA9 0.497 1.219 0.01515 22.3 20070410 215.2 55.8 271.0 6.8 0.420 0.858 ( 24d)

2007 AM 0.426 1.172 0.09695 21.6 20070410 314.8 172.5 107.2 11.7 0.467 0.799 ( 31d)

2007 AG 0.451 0.990 0.00419 20.1 20070410 317.3 5.6 283.3 11.9 0.374 0.720 ( 39d)

2006 YF13 0.548 1.290 0.08151 20.0 20070410 237.7 95.3 205.4 10.5 0.403 0.919 ( 55d)

2006 YM 0.787 1.009 0.02352 24.4 20070410 322.5 171.0 86.5 12.9 0.123 0.898 ( 8d)

2006 XP4 0.686 1.059 0.00411 23.9 20070410 301.6 343.3 296.8 0.5 0.214 0.872 ( 41d)

2006 XO4 0.586 1.092 0.02767 23.4 20070410 278.1 29.0 266.9 8.5 0.301 0.839 ( 25d)

2006 XX2 0.681 1.288 0.01722 25.1 20070410 195.5 67.6 260.7 17.5 0.308 0.985 ( 8d)

2006 WR127 0.566 1.248 0.19129 20.5 20070410 341.8 351.4 260.9 16.8 0.376 0.907 3

2006 WE4 0.641 0.928 0.10066 18.7 20070410 34.5 318.6 311.1 24.8 0.183 0.785 ( 25d)

2006 WO3 0.442 1.158 0.13238 21.4 20070410 334.6 9.7 252.7 21.2 0.447 0.800 ( 35d)

2006 WY2 0.656 1.311 0.25414 18.6 20070410 254.7 160.0 99.9 27.6 0.333 0.983 (112d)

2006 WX1 0.641 1.192 0.02873 19.6 20070410 326.8 290.9 328.1 11.6 0.300 0.917 ( 93d)

2006 WV1 0.588 1.068 0.01008 25.9 20070410 48.1 149.4 62.1 5.6 0.289 0.828 ( 1d)

2006 WB 0.696 1.003 0.00552 22.8 20070410 14.2 162.5 65.4 4.9 0.181 0.850 ( 16d)

2006 VB14 0.444 1.090 0.07889 18.9 20070410 42.5 346.4 258.8 31.0 0.421 0.767 ( 41d)

2006 VG13 0.570 1.066 0.04540 21.4 20070410 42.9 115.2 96.7 5.9 0.303 0.818 ( 33d)

2006 VY2 0.556 1.229 0.07559 22.7 20070410 60.2 327.0 231.3 14.6 0.377 0.893 ( 14d)

2006 VX2 0.662 1.204 0.02194 24.9 20070410 69.1 126.4 47.4 9.9 0.290 0.933 ( 5d)

2006 US216 0.278 0.995 0.04358 19.9 20070410 87.2 55.3 194.4 3.5 0.563 0.637 ( 30d)

2006 UZ215 0.706 1.074 0.01068 25.5 20070410 312.4 222.1 35.2 14.3 0.207 0.890 ( 4d)

2006 UL185 0.421 1.268 0.20333 21.3 20070410 355.8 177.3 52.3 19.4 0.502 0.844 ( 20d)

2006 UY64 0.785 1.078 0.05432 19.5 20070410 316.0 210.9 30.8 26.2 0.158 0.932 (123d)

2006 TU7 0.452 1.250 0.02274 21.9 20070410 126.9 68.6 92.0 2.9 0.469 0.851 ( 11d)

2006 TS7 0.398 1.495 0.01556 21.2 20070410 103.8 299.7 225.5 5.5 0.580 0.947 ( 18d)

2006 TL 0.566 1.314 0.04502 24.0 20070410 107.4 315.2 195.5 11.6 0.398 0.940 ( 16d)

2006 SU217 0.814 1.158 0.02570 25.4 20070410 311.8 38.2 194.4 2.6 0.175 0.986 ( 15d)

2006 SF77 0.619 1.226 0.06116 21.7 20070410 325.9 224.4 1.3 32.5 0.329 0.922 ( 23d)

2006 SP19 0.623 1.139 0.04532 24.2 20070410 84.2 166.0 358.6 4.6 0.293 0.881 ( 31d)

2006 SF6 0.683 1.216 0.01900 20.0 20070410 43.7 305.5 228.2 5.9 0.280 0.949 ( 63d)

2006 SE6 0.527 1.083 0.03679 22.9 20070410 103.1 182.9 347.5 4.8 0.345 0.805 ( 30d)

2006 RO36 0.697 1.115 0.11180 18.0 20070410 12.9 261.1 271.0 23.9 0.231 0.906 2

2006 RJ1 0.665 1.237 0.00140 22.3 20070410 349.5 110.3 93.5 1.4 0.301 0.951 ( 30d)

2006 QQ56 0.944 1.033 0.01746 25.9 20070410 70.1 330.0 161.6 2.8 0.045 0.988 ( 19d)

2006 QQ23 0.575 1.032 0.03360 19.6 20070410 148.6 124.8 5.0 3.4 0.284 0.804 ( 23d)

2006 NL 0.360 1.336 0.05676 19.7 20070410 92.3 29.3 115.3 20.1 0.576 0.848 ( 55d)

2006 MD12 0.331 1.346 0.22733 19.3 20070410 215.1 174.5 291.9 27.3 0.605 0.839 ( 64d)

2006 KZ39 0.292 0.939 0.06936 20.2 20070410 123.6 354.0 42.5 9.4 0.525 0.616 ( 2d)

2006 JF42 0.281 1.063 0.00288 19.0 20070410 12.8 17.7 41.0 6.0 0.582 0.672 2

2006 HV50 0.627 1.070 0.03275 23.6 20070410 223.3 22.6 34.8 16.4 0.261 0.849 ( 7d)

2006 HR29 0.726 1.245 0.09412 20.6 20070410 87.7 212.6 232.8 9.5 0.263 0.985 2

2006 HV5 0.576 1.116 0.01594 19.2 20070410 337.5 316.4 36.1 33.0 0.319 0.846 ( 4d)

2006 GB 0.787 1.131 0.01031 20.3 20070410 131.1 242.8 183.9 10.1 0.179 0.959 2

2006 FH36 0.765 1.144 0.01641 22.9 20070410 128.1 154.8 280.9 1.6 0.199 0.954 2

2006 FK 0.606 1.239 0.19408 21.3 20070410 218.8 3.1 15.2 14.6 0.343 0.923 2

2006 DM63 0.349 1.042 0.00072 26.7 20070410 110.5 17.4 336.4 1.8 0.498 0.695 ( 1d)

2006 DS14 0.573 1.154 0.15628 20.3 20070410 302.8 187.5 162.3 26.5 0.337 0.864 2

2006 CJ 0.166 1.187 0.02539 20.1 20070410 211.6 29.5 303.4 10.3 0.755 0.676 2

2006 BX147 0.259 1.313 0.03748 21.4 20060125 75.3 201.8 141.1 11.3 0.670 0.786 ( 0d)

2006 BQ147 0.474 1.166 0.07050 18.9 20070410 8.7 153.2 146.8 24.4 0.422 0.820 3

2006 BA9 0.578 1.247 0.07270 22.7 20070410 269.3 25.5 306.0 8.3 0.366 0.913 ( 32d)

2006 AM4 0.344 1.619 0.01103 21.8 20070410 15.6 139.7 123.3 4.1 0.649 0.982 2

2005 YV128 0.450 1.396 0.15472 20.5 20070410 236.9 191.7 127.8 14.1 0.512 0.923 2