- Mars facts:
- sidereal period = 687 days (how long it takes to complete a full
revolution around the sun)
- synodic period = 779.8 days (time taken from one conjunction to
another as seen from earth)
- equatorial diameter = 6,760km (cw. moon = 3,480km, earth =
12,760km, Jupiter = 142,800km)
- axial rotation = 24.6hrs
- mass = 0.107 x earth (cw. moon = 0.012, Jupiter = 317.9)
- 2 moons - Phobos & Deimos
- Opposition of Mars:
- Mars is closest to earth during an opposition. These occur on average once
every 780 days and range in proximity from 56m km to 100m km and thus these
are regarded as being "favourable" if close or
"unfavourable" if distant.
- The closer it is the bigger its apparent diameter as seen from earth and
thus the easier it is to see surface details and the brighter it becomes.
- its apparent size ranges from ~4" at its most distant to
20-25" at opposition (Jupiter is usually about 30-45")
- brightness as seen from earth = magnitude -1.8 to - 2.9
depending on distance at opposition down to +1.7 at most distant (cw.
brightest star Sirius = -1.58; venus -3.3 to -4.5; Jupiter -0.9 to -2.3;
Saturn +1.5 to +0.4;
- August 27th 2003, it came to 55.758m km, the closest for approx. 60,000
yrs. The next time it will be as close is in 288yrs.
- named after the Roman god of war because of its reddish tinge, and
identified in certain aspects with the Greek Ares, and under it, says the Compost
of Ptholomeus, "is borne theves and robbers...nyght walkers and
quarell pykers, bosters, mockers, and skoffers; and these men of Mars
causeth warre, and murther, and batayle. They wyll be gladly smythes or
workers of yron..lyers, gret swerers."
- among the alchemists, Mars designated iron.
- Keppler accepts the probable existence of Mars' two moons - presumably
based on Earth having 1 and Jupiter having "four".
- 1726: satirist Jonathan Swift in his "Gulliver's Travels"
talks of Mars' "two moons"
- 1877 Mars opposition (the finest since 1845):
- Asaph Hall using a 26" refractor discovers Mars' two moons
(Phobos & Deimos) by manoeuvring his eyepiece to keep mars out of
view and thus from blinding his ability to see the close, much dimmer
moons. Another method to attempt to see them is by adding an occulting
bar in the eyepiece to block the light coming from Mars.
- Nov 1879 Mars opposition:
- Schiaparelli using an 8.6" refractor in Milan discovers:
- a tiny white spot he called Nix Olympica ("Snow of
Olympus") which he thought was snow on Olympus Mons, but is
actually reflected light of the canopy of orographic clouds over its
peak which frequently form over the summit after noon as winds carry
warm, moisture-laden air over the peaks with resulting freezing of
the water to form ice on the leeward (western) side of the summits.
This can be seen in good seeing in a 6" reflector esp. if a
blue filter is used to improve contrast. These are most likely to be
present when the water vapour content of the atmosphere is greatest
- northern hemisphere spring/early summer when polar ice melting
& early in southern hemisphere spring when ice in Hellas &
Argyre basins is subliming. The clouds may coalesce over the Tharsis
mountains forming a W cloud that was 1st reported in 1954. The
clouds usually disappear during the cold Martian nights.
- ribbon-thin canali ("channels")
- Ascraeus Lacus ("Lake of Ascra") - the shield volcano we
know know as Ascraeus Mons
- 1892 Mars opposition:
- William Henry Pickering using a 13" refractor in the Andes:
- charted dozens of additional "lakes", chiefly at the
points where Schiaparelli's canali intersected - a few years later
suggested that these might be volcanic craters rather than water
- found that he could distinguish a dark circular spot against a
bright background with a 10" telescope if it subtended an
apparent angle of 0.20", exceeding Dawe's limit based on
splitting double stars by a factor of 2.3. When Mars disc has an
apparent diameter of 20" (eg at opposition), a feature on Mars
68km in diameter will subtend 0.20", thus the 3 largest summit
calderas should just be within the reach of a 10" telescope in
- 1894 Mars opposition:
- Edward Emerson Barnard using a 36" refractor at Lick Observatory
atop California's Mount Hamilton:
- detailed sketches of Martian surface including Arsia Mons, Olympus
Mons as dark spots
- 1898, H.G.Wells wrote The War Of The Worlds, in which he recounted
the horrors of a war from invading martians on earth.
- 1903: Lowell using a 24" refractor when Mars disc was 12.6"
- "global network of irrigation canals" based on his
preconceived notion that Mars surface was smooth & level. This
optical illusion perpetuated this misconception for many years.
- most astronomers before space probes obtained close-up images believed it
was a windswept wasteland devoid of any dramatic topographic features
- 1st three Mariner spacecraft that flew past Mars snapped high-resolution
images of less than 1/5th of its surface, but unfortunately, this fraction
was not a representative sample as they showed bleak, monotonous landscapes
peppered with hundreds of eroded impact craters which seemed to verify the
dour expectations of a geologically uninteresting world
- Nov 1971: Mariner 9 space probe orbited Mars to map it from pole to pole,
but a global dust storm was raging that gave it the appearance of a
featureless ball of orange wool. As the storm abated, a very different world
was revealed - summits of 4 enormous volcanoes, looking like islands in a
sea of dust. The largest, Olympus Mons, towers to a height of 21.3km -
nearly 2.5x height of Mt Everest, with a base of 550km diameter. Its three
smaller neighbours, the Tharsis Montes - Ascraeus Mons, Pavonis Mons &
Arsia Mons - each rise ~15km and are arrayed in a line known as the Tharsis
- 1976, Viking 1 takes the famous "face on Mars" photo - a
rock formation 2.5km wide which gives the illusion of it being a human face,
but some developed theories of the Egyptian pyramids especially as the
Mariner 9 image showing "pyramids" on Mars in the plain of Elysium
which had sides 13x the size of Giza's Great Pyramid in Egypt .
- 4 of the 6 closest oppositions in the 20thC featured planet-encircling
dust storms that shrouded the planet surface for weeks.
- 1998: Mars Global Surveyor supplied new & revealing images.
What can one see on Mars?
- here is a pic of mars taken from the Hubble Space Telescope without
Earth's interfering atmosphere
- below are simulations of how Mars would
appear at opposition through telescopes with apertures from 2.4" to 12" under very good seeing condition
turbulence (more typical of observing conditions):
If you are having difficulties seeing anything but a blob then consider:
1. Are the optics of your scope good quality. Bad optics will never focus
sharply and image contrast will always be poor. In a reflecting telescope if the
mirror is homemade, has it been tested so that you know if it can perform well?
2. Collimation, (optical alignment) could be the problem. Visit this site on
how to fix this and many other telescope problems. http://astronomy.trilobytes.com.au/scope/fix-it.htm
3. Bad seeing (turbulence). If
Mars is low in the sky, atmospheric turbulence can obliterate contrast and
detail on the planet. Wait for it to gain altitude say greater than 30 degrees.
Sometimes seeing may be bad even when Mars is high. It depends on atmospheric
conditions at the time.
4. Speaking of turbulence. Thermal currents inside the telescope tube will
have a similar effect if the scope is transported from a warm interior to cold
outdoors. Allow the scope 1/2hr to 1hr to reach thermal equilibrium outdoors
before beginning to search for planetary detail.
5. Even in an 8" with good optics and good seeing conditions the
dusky markings on the planet require some patience and practice to discern
especially if you are new to observing. The bright polar cap however should be
6. In a 3.5" Maksutov, The polar cap is always visible and the most
prominent markings (Sinus Sabius, Syrtis Major, Mare Sirenum, Mare
Cimmerium and the dark hood around the ever shrinking polar cap) are
identifiable most of the time. They are better with a homemade 6"
7. Sometimes a larger aperture performs worse than a smaller aperture under
bad seeing conditions. You may have been caught out by this. It depends on the
prevailing general seeing conditions in your locality which may be determined by
season, adjacent buildings, bodies of water, vegetation and other such factors.
You might like to try a 4" or 6" aperture mask over the top end of the
scope to see if this beats the seeing conditions. It might also cure a badly
figured homemade mirror if that is the problem.
8. A red or orange filter will help if the seeing is good to begin with.
Otherwise it makes little difference. On a recent occasion an orange filter
improved the contrast on Mars in the 3.5" Maksutov but made no difference
in the 6". A filter however, even if it does nothing else, can reduce the
"glariness" of the planet so that it is easier on the eye.
9. Provided the optics in your scope are good to begin with, keep on
persisting with the above points in mind and you are sure to get a good night
when Mars will deliver! As a rule, with good optics, under good seeing
conditions, a larger aperture will always outperform a smaller one.
- NASA's Mars Global Surveyor and Mars
Odyssey missions have provided evidence of a recent
ice age on Mars. In contrast to Earth's ice ages, a martian
ice age waxes when the poles warm up and water vapor
is transported toward lower latitudes.
Martian ice ages wane when the poles cool and lock
water into polar icecaps.
- The "pacemakers" of ice ages on Mars
appear to be much more extreme than the comparable
drivers of climate change on Earth.
Variations in the planet's orbit and tilt produce
remarkable changes in the distribution
of water ice from polar regions down to latitudes
equivalent to Houston or Egypt.
- Researchers, using NASA spacecraft
data and analogies to Earth's Antarctic Dry Valleys,
report their findings in the Thursday, Dec. 18 2003
edition of the journal Nature. "Of
all the solar system planets, Mars has the climate
most like that of Earth. Both are sensitive to small
changes in orbital parameters," said planetary
scientist Dr. James Head of Brown University,
Providence, R.I., lead author of the study. "Now
we're seeing that Mars, like Earth, is in a period
between ice ages."
- Discoveries on Mars, since 1999, of relatively
recent water- carved gullies, glacier-like flows,
regional buried ice and possible snow packs created
excitement among scientists who study Earth and other
planets. Information from the Mars Global Surveyor and
Odyssey missions provided more evidence
of an icy recent past.
- Head and his co-authors from Brown (Drs. John
Mustard and Ralph Milliken), Boston University (Dr.
David Marchant) and Kharkov National University,
Ukraine (Dr. Mikhail Kreslavsky) examined global
patterns of landscape shapes and near-surface water ice
mapped by the orbiters. They concluded
that a covering of water ice mixed with dust mantled
the surface of Mars to latitudes as low as 30 degrees,
and is now degrading and retreating. By observing the
small number of impact craters in those features and by
backtracking the known patterns of
changes in Mars' orbit and tilt, they estimated the most
recent ice age occurred just 400,000 to 2.1 million
years ago, very recent in geological terms.
"These results show that Mars is not a dead
planet, but it undergoes climate changes that are even
more pronounced than on Earth," Head said.
- Marchant, a glacial geologist who has spent 17
field seasons in the Mars-like Antarctic Dry Valleys,
said, "These extreme changes on Mars provide
perspective for interpreting what we see on Earth.
Landforms on Mars that appear to be related to climate
changes help us calibrate and understand similar
landforms on Earth. Furthermore, the range of microenvironments
in the Antarctic Dry Valleys helps us read the Mars
- Mustard said, "The extreme climate changes on
Mars are providing us with predictions we can test
with upcoming Mars missions, such as Europe's Mars
Express and NASA's Mars Exploration Rovers. Among
the climate changes that occurred during these extremes
is warming of the poles and partial melting of water
at high altitudes. This clearly broadens the
environments in which life might occur on Mars."
- According to the researchers, during
a martian ice age, polar warming drives water vapor from
polar ice into the atmosphere. The water comes back to
ground at lower latitudes as deposits of frost or snow
mixed generously with dust. This ice-rich mantle, a
few meters or yards thick, smoothes the contours
of the land. It locally develops a bumpy texture at human
scales, resembling the surface of a basketball and
also seen in some Antarctic icy terrains. When ice at
the top of the mantling layer sublimes back into the
atmosphere, it leaves behind dust, which forms an
insulating layer over remaining ice. On Earth, by contrast,
ice ages are periods of polar cooling. The buildup of
ice sheets draws water from liquid-water oceans, which
Mars lacks. "This exciting new
research really shows the mettle of NASA's
'follow-the-water' strategy for studying Mars,"
said Dr. Jim Garvin, NASA's lead scientist for Mars
exploration. "We hope to continue pursuing this
strategy in January, if the Mars Exploration Rovers land
successfully. Later, the 2005 Mars
Reconnaissance Orbiter and 2007 Phoenix near-polar lander
will be able to directly follow up on these astounding
findings by Professor Head and his team." Global
Surveyor has been orbiting Mars since 1997, Odyssey
since 2001. NASA's Jet Propulsion Laboratory, a
division of the California Institute of Technology,
Pasadena, manages both missions for the NASA
Office of Space Science, Washington, D.C.
- Information about NASA's Mars missions
is available on the Internet at: http://mars.jpl.nasa.gov.