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Solar System Astrometry
Carlos E. Lopez
Universidad Nac. de San Juan, Argentina, and
Yale Southern Observatory
Measuring the Positions of:
9Natural Satellites
9Space Debris
Ptolomy’s Solar System
Copernicus’s scheme of the Solar System
The Solar System Before 1801
The Solar
System on
Jan 1st,
1801 accepted)
(and after
the Copenican
had been
The Solar System as of Jun 8, 2005
around 150,000 objects
An Outer Belt?
The Kuiper belt is thought to be the source of short-period
comets and of centaurs. It is named after Gerard Kuiper who
in 1951 but is also sometimes
referred to as the Edgeworth-Kuiper belt, in recognition of
the amateur astronomer Kenneth Edgeworth (1880-1972)
who, in his only scientific paper, published in the Journal of
the British Astronomical Association in 1942, was the first to
suggest the existence of a region of comet-like objects
beyond the outer planets. The first observational support for
it came in 1992 when David Jewitt of the University of
Hawaii and Jane Luu of the University of California, Berkeley
discovered a 200-kilometer-wide object circling the Sun
beyond the orbit of Pluto.
Orbit of 1996 TL66
The Outer Solar System by the End of 1999
How many TNOs have been identified so far?
9 As of Jul 12, 890 objects have been identified. It
is assumed there must be on the order of 70,000
such objects.
9 The first TNO ever discovered was 1992 QB1.
9 The last one to be discovered was 2005 JR179.
Discovery rate
The name of an Asteroid could be:
Provisional Designations
Provisional Designations (cont.)
¾If there are more than 25 discoveries in any one half-month period, the
second letter is recycled and a numeral `1' is added to the end of the
designation. If more than 50 discoveries, the second-letter is again recycled,
with a numeral ‘2' appended after the second letter. Discoveries 76-100 have
numeral ‘3' added, numbers 101-125 numeral `4', etc. When possible, these
additional numbers should be indicated using subscript characters.
¾Thus the order of assignment of designations in a particular half-month
period is as follows: 1995 SA, 1995 SB, ..., 1995 SY, 1995 SZ, 1995 SA1,
..., 1995 SZ1, 1995 SA2, ..., 1995 SZ9, 1995 SA10, etc.
The provisional designations stored on the orbit
and observations is stored in a 7-character
packed format
J95X00A = 1995 XA
J95X01L = 1995 XL1
J95F13B = 1995 FB13
J98SA8 Q = 1998 SQ108
J98SC7V = 1998 SV127
J98SG2S = 1998 SS162
K99AJ3Z = 2099 AZ193
From temporary to provisional designations
9 2005 OH = 5O5604D(July 20.49 UT)
9 2005 OE = 5O3EC49(July 19.47 UT)
9 2005 OB = 77G001 (July 18.37 UT)
9 5NA1C16 does not exist (July 17.93 UT)
9 P03DDA does not exist (July 17.49 UT)
9 2005 NP82 = 5N5545E(July 17.49 UT)
9 2005 NW80 = SW40Pz (July 16.66 UT)
9 2005 NV80 = UHAZ01 (July 16.66 UT)
Asteroids: Areas for Study
9 Shape and Structure
9 Composition
9 Mass
9 Surface Structure
9 Moons
9 Magnetometry
Classification of Asteroids
The classification can be made from
two very different points of view:
9 Physical characteristics
9 Location within the Solar System
Physical Characteristics (main classes only)
C class: they have a dark appearance, implying a composition of
rocky material mixed with dark carbon compounds. This class is
thought to consist of primitive matter.
S class: this is a rather small group –compared with the C ones.
They are more reflective and show a preponderance of silicate
rock. This is the S class, which stands for stony class.
M class: this group consists of bodies with large amounts of metal,
such as iron and nickel. Apparently these asteroids come from
differentiated bodies that have fractured by collisions.
V class: a small number of asteroids have basaltic surfaces. These
basaltic asteroids evidently had great flows of lava.
D class: a few asteroids having a dark surface. In fact the
surface of many of these is dark red. Several of these asteroids,
beyond the orbits of Saturn, are called Centaur asteroids.
Distribution of Inclinations
Kirkwood Gaps
Dsitribution of the Lagrangian Points
The Inner Most Solar System
Classification of NEAs
Conversion Between Absolute Magnitude (H) and Diameter
The Beginning
"The potential catastrophe of an asteroid hitting Earth should no longer be
ignored. We need to know what is out there. Accounts of asteroids
passing close to Earth with almost no prior warning should be enough to get
our attention. The first step is to assess the threat. Given the vast
number of asteroids and comets that inhabit the Earth's neighborhood,
greater efforts for tracking and monitoring these objects are critical.
This bill would direct NASA to expand their current program to track and
detect potential threats and would provide a funding authorization. Any
threat that would wreak havoc on or world should be studied and
prevented if possible. We have the technology, we need the direction this bill provides that."
Rep. Rohrabacher
The Beginning (cont.)
"All of these bills will improve our lives through increasing our
understanding of the Earth, how it works and what may
threaten it."
Science Committee Chairman Sherwood Boehlert
Search Programs
The Discovery Channel Telescope
The only requirements for participation in the FMO project are 1) interest, 2)
sharp eyes and 3) access to a computer during the hours that the
Spacewatch mosaic system is in operation. If you are interested in
participating, please refer to How to Find FMOs for more information.
The Ritcher’s Scale of Asteroid Impacts
Upcoming Ecounters
How Many NEAs are there?
9 286 Atens
91662 Apollos
91471 Amors
IAU Minor Planet Center
IAU Minor Planet Center
IAU Minor Planet Center
IAU Minor Planet Center
Results should be submitted in the MPC format:
9 COD (observatory code) (YSO = 808)
9 CON (followed by the contact details)
9 OBS (followed by the list of observers)
9 MEA (followed by the list of measurers)
9 TEL (followed by details of the telescope)
9 NET (followed by the abbreviated name(s) of the catalogue(s) used for the reductions).
9 BND (followed by single character representing the mag band)
9 COM (followed by a textual comment)
9 NUM (followed by a count of the observations in this batch)
Accepted Detectors
P Photographic (default if column is blank)
E Encoder
T Meridian or transit circle
M Micrometer
V/v "Roving Observer" observation
R/r Radar observation
S/s Satellite observation
c Corrected-without-republication CCD observation
Reference Catalogues Recommended by
the IAU Minor Planet Center
9USNO A2.0
9Tycho 2
9USNO B1.0
9GSC 2.2
Image mining
image mining facility for moving objects
Addition of the three previous singlets
Asteroid 2002 NT7 detected by NEAT
The DSS Plate Finder
1999 AN10
POSS Image obtained in 1955, 34 years before the
official discovery of the asteroid!!!
A new asteroid?
Radar-Detected Asteroids
97 Main-Belt Asteroids
175 Near-Earth Asteroids
Radar Observations
High-resolution Model of Asteroid 4179 Toutatis
Hudson, R. et al., 2003, Icarus, 161, 346
Current Status
Coming Radar Observations
Radar Observations (cont.)
Major Planets and Satellites
Galileo’s notes on the discovery of the “Medicean planets”
On the 7th day of January in the present year, 1610, … I noticed
a circumstance which I had never been able to notice before,
namely that three little stars, small but very bright, were near
the planet; and although I believed them to belong to a number of
the fixed stars, yet they made me somewhat wonder, because they
seemed to be arranged exactly in a straight line, parallel to the
ecliptic… I therefore concluded, that there are three stars in the
heavens moving about Jupiter, as Venus and Mercury around the
Sun …
Orbits of Jupiter’s Known Satellites
Discovery Images of S/2000 J8
(taken with the University of Hawaii 88-inch
telescope + 8-K CCD Camera)
Pascu, D. et al. 1987. AJ 93, 963-1007.
Contour Density of Uranus and …
Veiga, C., and Vieira Martins. 1995, A&ASS, 111, 387-392
Veiga, C., and Vieira Martins. 1995, A&ASS, 111, 387-392
Veiga, C., and Vieira Martins. 1995, A&ASS, 111, 387-392
Observing Mars Satellites
Colas, F., and Arlot, J. 1991, A&A, 252, 402
Space Debris
1. In its resolution 51/123, paragraph 32, of 13 December 1996, the General
Assembly considered it essential that Member States pay more attention to
the problem of collisions of space objects, including nuclear power sources,
with space debris, and other aspects of space debris, and called for the
continuation of national research on that question, for the development of
improved technology for the monitoring of space debris and for the
compilation and dissemination of data on space debris. To the extent
possible, the Assembly considered that information thereon should be
provided to the Scientific and Technical Subcommittee of the Committee on
the Peaceful Uses of Outer Space.
Low Earth Orbits
(between the surface of the Earth and 2,000 km)
Geosynchronous Region
(around 35,785 km altitude)
Space Debris Facts
9Since 1961, more than 170 man-made objects in Earth orbit
have undergone moderate to serious breakups.
9Another 40 have undergone less energetic debris-producing
9Only three of these fragmentations are known to have been
caused by deliberate or accidental collisions.
9The vast majority of fragmentations appear to have arisen from
explosions involving residual propellants or pressurants, battery
malfunctions, self-destruction charges, or space defense
IAU Minor Planet Center
IAU Minor Planet Center
IAU Minor Planet Center
Stellar Occultations by
Solar System Objects
The IOTA Home Page
The Occultation Path of 1300 Marcelle
The Occultation Path of 203 Pompeja
Yale Southern Obs.
The Diameter of Juno from its Occultation of AG +0º 1022
The Observations are well represented by a mean elliptical limb profile having semimajor
and semiminor axes of 145.2+0.8 and 122.8+1.9 km (Millis, R. et al. 1981, AJ 86, 306)
The discovery of Uranu’s rings
Light variations of SAO 158687 as it was being
occulted by Uranu’s disk in 1977
Occultations Predicted for July 2005
Jul 03 - Asteroid 496 Gryphia Occults HIP 69127 (6.5 Magnitude Star)
Jul 07 - Jupiter Occults PPM 178840 (10.2 Magnitude Star)
Jul 13 - Moon Occults Jupiter
Jul 14 - Asteroid 253 Mathilde Occults TYC 5684-00949-1 (11.3 Magnitude Star)
Jul 15 - Asteroid 14 Irene Occults HIP 75118 (6.1 Magnitude Star)
Jul 22 - Asteroid 39 Laetitia At Opposition (9.6 Magnitude)
Jul 23 - Asteroid 538 Friederike Occults HIP 88504 (7.5 Magnitude Star)
Jul 29 - Asteroid 1233 Kobresia Occults HIP 18491 (7.5 Magnitude Star)
Extrasolar Planetary Systems
The Martir
Filippo (Giordano) Bruno (1548 – 1600)
Bruno’s Thoughts
9Bruno affirmed that the universe was homogeneous, made up everywhere
of the four elements (water, earth, fire, and air), rather than having
the stars be composed of a separate quintessence. Essentially, the same
physical laws would operate everywhere in the universe.
9Under Bruno’s model, the Sun was simply one more star, and the stars
all suns, each with its own planets. Bruno saw a Solar System of a
sun/star with planets as the fundamental unit of the universe.
9According to Bruno, infinite God necessarily created an infinite universe,
formed of an infinite number of solar systems, separated by vast
regions full of Aether, because empty space could not exist. (Bruno did
not arrive at the concept of a galaxy.)
9Each comet is a world, a permanent celestial body, formed of the four
Gerard Peter Kuiper (1905 – 1973)
His observations led him to conclude in 1935 that the
average separation between the components of binary
stars was about 20 AU, which is similar to the distance
of the gas giants from the Sun…
Extrapolating from the fact that about 10% of binaries
contained companion stars that were one-tenth or less
as massive as the primaries, Kuiper suggested there
might be 100 billion planetary systems in our Galaxy
Searching for Extrasolar Planets
Two Basic Methods
Direct Detections
Indirect Detections
Indirect Detections
Astrometry is used to look for the periodic wobble that a planet
induces in the position of its parent star.
Doppler spectroscopy is used to detect the periodic velocity shift
of the stellar spectrum caused by an orbiting giant planet.
Transit Photometry:
Photometry measures the periodic dimming of the star caused by a
planet passing in front of the star along the line of sight from the
The apparent orbit of the Sun around the center of mass of the Solar System
from 1960 to 2025. The tic marks are in intervals of 0.2 mas.
Apparent radial velocity of the Sun as it orbits the centrer of mass of
the Solar System from 1960 to 2025 as viewed from the vernal
Title: Proposal for a project of high-precision stellar
radial velocity work
Author: Otto Struve
Journal: The Observatory, Vol. 72, p. 199-200 (1952)
Submission Date: 24 July 1952
Publication Date: October 1952
Transit Photometry
Transit of Venus, June 2004
Second contact
June 8, 2004, 05:39:47.7 UT
Lasne, Belgium
Third contact
June 8, 2004, 11:03:59.8 UT
Lasne, Belgium
Planetary Transit in HD 209458
Artwork by Lynette Cook
Transit in HD 2049458: light variation
Some Results from the University of New South
Wales Extrasolar Planets Search
Hidas, M. et al. 2005. MNRAS, 360, 703.
The Future
Mission facts
9 Darwin will use a flotilla of six space telescopes, each of which will
be at least 1.5 metres in diameter. They will work together to scan the
nearby Universe, looking for signs of life on Earth-like planets.
9 At optical wavelengths, a star outshines an Earth-like planet by a
billion to one. Partly to alleviate this difficulty, Darwin will observe in
the mid-infrared. At these wavelengths, the star-planet contrast
drops to a million to one, making detection somewhat more manageable.
9Another key reason for observing in the infrared is because life on
Earth leaves its mark at these wavelengths.
9To see planets around nearby stars would require a telescope of
roughly 30 metres in size and this is way beyond the current limits of
technology. To overcome this limitation, Darwin will use six telescopes.
Mission facts
9OBSS is an astrometric satellite designed to determine with unprecedented
accuracy the positions, distances, and motions of a billion stars within our
9OBSS will be optimized for the detection of extrasolar giant planets of 10
Jupiter masses and less, orbiting all Sun-like stars within 300 light-years of
the solar system with orbital periods of up to 10 years.
9OBSS will detect more than 80 percent of near asteroids with a radius
greater than 140 meter. It will also detect hundreds of new Kuiper Belt and
trans-Neptunian objects.
9OBSS will yield a comprehensive characterization of stars in a volume that
will encompass half the Galaxy, including the solar neighborhood and the
galactic nucleus.
9The OBSS's 1-metre optical telescope would orbit the Sun for five years. It
would view each star about 400 times to pinpoint stellar positions to a
precision of 100 microarcseconds - 10 times the accuracy of Hipparcos.
NASA finds conclusive evidence there once
was water on Mars