Lunar Meteoroid Impacts and How to Observe Them

242 Pages·2009·6.525 MB·English

by  Brian Cudnik (auth.)

Astronomers’ Observing Guides
For other titles published in this series, go to
www.springer.com/series/5338
Brian Cudnik
Lunar Meteoroid
Impacts and How
to Observe Them
with 116 Illustrations
Brian Cudnik
Houston, TX
USA
[email protected]
Series Editor
Dr. Mike Inglis, BSc, MSc, Ph.D.
Fellow of the Royal Astronomical Society
Suffolk County Community College
New York, USA
[email protected]
ISBN 978-1-4419-0323-5 e-ISBN 978-1-4419-0324-2
DOI 10.1007/978-1-4419-0324-2
Springer New York Dordrecht Heidelberg London
Library of Congress Control Number: 2009930463
© Springer Science+Business Media, LLC 2009
All rights reserved. This work may not be translated or copied in whole or in part without the written
permission of the publisher (Springer Science+Business Media, LLC, 233 Spring Street, New York, NY
10013, USA), except for brief excerpts in connection with reviews or scholarly analysis. Use in connection
with any form of information storage and retrieval, electronic adaptation, computer software, or by similar
or dissimilar methodology now known or hereafter developed is forbidden.
The use in this publication of trade names, trademarks, service marks, and similar terms, even if they
are not identified as such, is not to be taken as an expression of opinion as to whether or not they are
subject to proprietary rights.
Printed on acid-free paper
Springer is part of Springer Science+Business Media (www.springer.com)
Foreword
d
r
o
w
e
r
o
F
The genesis of modern searches for observable meteoritic phenomena on the
Moon is the paper by Lincoln La Paz in Popular Astronomy magazine in 1938. In it
he argued that the absence of observed flashes of meteoritic impacts on the Moon
might be interpreted to mean that these bodies are destroyed as luminous meteors
in an extremely rarefied lunar atmosphere. The paper suggested the possibility of
systematic searches for such possible lunar meteors.
With these concepts in mind, I was surprised to note a transient moving bright
speck on the Moon on July 10, 1941. It appeared to behave very much as a lunar
meteor would – except that the poorly estimated duration would lead to a strongly
hyperbolic heliocentric velocity. Thus, the idea of systematic searches for both pos-
sible lunar meteors and meteoritic impact flashes was born. It was appreciated that
much time might need to be expended to achieve any positive results. Systematic
searches were carried out by others and myself chiefly in the years 1945–1965 and
became a regular program at the newly founded Association of Lunar and Planetary
Observers, or ALPO.
It was obvious that such searches were best attempted with the lunar back-
ground as faint as possible. Thus, one opportunity was on the earthlit regions soon
before or after New Moon. In concept the best chance then was with a crescent as
close to New Moon as possible, but in practice there were complications: the need
for a dark sky free of dawn or twilight lighting and the requirement that the Moon
be not too near the observer’s horizon. A second kind of opportunity came during
lunar eclipses, with a preference for the darker eclipses.
It was appreciated that a single observation of an apparent meteoritic impact
(stationary flash) or apparent lunar meteor (moving bright spot) was inconclu-
sive. It was necessary to have a second observation of the same feature at the
same time and at the same position on the Moon. The ALPO observers did indeed
report many flashes and many moving bright specks. However, there was never
the essential duplicate confirming observation. In truth it proved very difficult to
get independent and widely separated amateur observers to carry out simultane-
ous observations of the whole earthshine or a selected specific portion thereof.
(An excellent time for an observer in Illinois in terms of dark sky and Moon’s
altitude may be useless for his cooperating colleague in Colorado or Georgia).
Of course, we now know that the lunar atmosphere is far too tenuous to per-
mit lunar meteors to exist. We also know that the very great majority of mete-
oritic impact flashes will be too faint and too brief in duration to be detected
by telescopic visual observers. It remained for Brian Cudnik and others to
achieve the first confirmed observations of impact flashes during the Leonid
epoch in 1999.
It is easy, of course, to dismiss the old unconfirmed observations as nothing but
illusions. However, some of the observers, including myself, were confident of
having seen something, regardless of ideas about its interpretation. Very few of the
v
objects recorded can be terrestrial meteors coming from the direction of the
Moon. Perhaps there is a very slight chance that the observers witnessed some
unknown or poorly studied phenomenon.
d
r Walter H. Haas
o
w
e
r
o
F
vvviii
Contents
Foreword........................................................... v
Introduction........................................................ xi
Part I The Moon and Meteoroids
Chapter 1 Widespread Evidence ...................................... 3
A Brief History of Impacts in the Early Solar System ........... 3
The Impact that Built the Moon ............................. 6 s
t
A Brief Look at Some Other Significant Impacts............... 8 n
e
Are Impacts Still Happening Today? ......................... 15
t
n
o
Chapter 2 Lunar Impact Features..................................... 17 C
Maria vs. Highland Craters ................................. 17
Young vs. Old Craters ...................................... 18
Appearance vs. Size........................................ 21
How to Recognize Different Types of Features................. 24
Chapter 3 Remarkable Collisions ..................................... 27
Historic Impacts of Interest................................. 27
The AD 1178 Lunar Impact Event............................ 28
The Taurid Complex Objects................................ 29
The “Lunar Flare” Event of 1953 ............................. 30
Chapter 4 Possible Impact Phenomena (PIPs).......................... 35
Probable Appearance and Classification of PIPs ............... 35
1955–2008: Additional Events ............................... 43
A catalogy of Coordinated and/or Shower-Related
Events as Documented by ALPO and IOTA ................... 48
The Perseid Meteor Shower: 12–14 August 2002 ............... 59
Chapter 5 Beyond the Moon ......................................... 71
Target Jupiter: The Shoemaker-Levy 9 Multiple Impact Event.... 72
Crater Types and Morphologies Throughout the Solar System... 74
Other Historic and Probable Impact Sightings
on Other Worlds .......................................... 92
Conclusions .............................................. 95
vii
Part II An Observer's Guide to Lunar Meteor Impacts, Past and Present
Chapter 6 Guide to Observing Impact Features on the Moon............. 99
Maria vs. Highland Cratering ............................... 101
Young vs. Old Craters ...................................... 102
Appearance vs. Size....................................... 104
How to Recognized Different Types of Features............... 106
A “Top 100” List of significant Impact Structures to Observe ... 109
A Link to Astronomical League Observing Clubs Related
to the Moon ............................................. 110
Chapter 7 Impacts Today ........................................... 111
Lunar Transient Phenomena and Lunar Meteoroid Impacts .... 111
Some Possible Causes of LTP............................... 112
Narrowing Down the Causes of LTP to Three: Electrostatic
Levitation, Tidal/Thermal Stresses, and Meteoroid Impacts .... 114
s
t Chapter 8 Lunar Impact Observation Programs ....................... 121
n
Past Campaigns .......................................... 121
e
t Current Programs ........................................ 122
n
o Space Missions that Impacted/Will Impact the Moon.......... 123
C
Mission Statement of the ALPO Lunar Meteoritic Impact
Search Program: A Vision of Lunar Impact Research .......... 125
Chapter 9 Observing Impacts as They Happen (with Contributions
by Many Members of the International Occultation
Timing Association)...................................... 127
Geometric Considerations and Preparations Needed
for Making Observations .................................. 128
Techniques for Visual Observations . . . . . . . . . . . . . . . . . . . . . . . . . 129
Techniques for Video Observations ......................... 130
Twelve Examples of Observer Equipment Setup and Use....... 133
Some Examples of Products and Resources .................. 142
Putting it All Together: A Lunar Meteor Observing Plan ....... 150
Conclusion .............................................. 152
Chapter 10 Finding Collisions........................................ 153
Automated Impact Detection Software ...................... 153
The Use of Registax for Automated Lunar Meteor Detection.... 154
Increasing the Probability of Detection with LunarScan ....... 158
Chapter 11 Spurious Flash or True Impact Event?....................... 165
How to Identify True Lunar Meteoritic Impact Events ......... 165
GLR Dark Test ........................................... 165
Validation of Lunar Flashes: A Network of Observers
for Simultaneous Patrols .................................. 168
Identification of the Flash Profiles .......................... 171
Single Observer Validation of Lunar Meteor Impacts .......... 175
Conclusion .............................................. 178
viii
Chapter 12 Professional and Amateur Collaboration.................... 181
Introduction: Pro-Am Collaborations ....................... 181
Examples of Professional Research in Lunar Meteor Impacts ... 182
Advances in Amateur Lunar Meteor Observations ............ 189
Appendix A References.............................................. 197
Appendix B Glossary................................................ 199
Appendix C Impact Candidates Observed by ALPO/LMIS Likely
to be Cosmic Ray Hits or Other Spurious Phenomena ........ 209
Introduction............................................ 209
1999: Lunar Geminid Impact Candidates ................... 209
May 2000: Lunar Eta Aquarid Impact Candidates ............ 210
The Leonid Meteor Storms of 2001......................... 211
The Perseid Meteor Shower: 12–14 August 2002 ............. 211
s
Appendix D A Simple Method for Timing Videotaped Occultations t
n
(and Lunar Meteor Impact Flashes)........................ 215
e
Introduction............................................ 215 t
n
System Requirements .................................... 215 o
C
System Setup ........................................... 215
Timing the Occultation................................... 217
Conclusion ............................................. 219
Appendix E E quipment Checklist and Vendors ......................... 221
Appendix F Details of Shortwave Time Signals for Astronomical Timings .. 225
Appendix G S tellar Resources for Comparison and Calibration ........... 229
Finding Limiting Magnitudes for Visual
and Video Camera Observation ........................... 229
Standard Stars for Extinction Correction
and Flux Calibration..................................... 231
Appendix H I mpact Plots............................................ 233
Index.............................................................. 237
ix
Introduction
On November 18, 1999, the first scientifically confirmed lunar meteoritic impacts
were recorded in the form of pinpoint flashes that resulted from the collision of the
Moon with debris within the Leonid meteoroid stream. (The locations of the first
seven of these appear in Fig. 1; an image of the “A” impact appears in Fig. 2). These
fragments, traveling at 71 km/s (44 mi./s) impacted the Moon with such force that
the optical flashes of these explosions were visible from nearly a quarter of a mil-
lion miles away. Similar events were observed during the 2001 Leonid display, with
two events each confirmed independently by at least two observers. In all of these
cases, the impacts had the appearance of stars, ranging in brightness from third to
eighth magnitude, and each appearing for less than 1/20th of a second. These
events resulted in the rebirth of the lunar meteoritic impact observing section of
the Association of Lunar and Planetary Observers and have revived interest in
lunar impact phenomena and lunar transient phenomena (LTP) (also called tran-
sient lunar phenomena).
LTP is a term that refers to lunar change. The Moon was once thought to be a
completely dead world geologically speaking, with no observable change. However,
there are many astronomers, some of whom are very experienced observers, who
have no doubt that they observe change on the Moon in the form of fogs and hazes;
localized color changes; flashes of various brightnesses, sizes, frequencies, and
colors; and other dramatic visible manifestations. The problems with these obser- n
o
vations are that they cannot be easily reproduced and also often lack a second,
i
t
c
u
d
o
r
t
n
I
Fig. 1. The historic moon map showing the locations of the first six Lunar Leonid Meteors of 1999 (Courtesy of David Dunham and IOTA)
xi