A close encounter with Mars
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A close encounter with Mars
The Red Planet makes its nearest approach to Earth
in 1999 this week and next
Once in about every fifteen years a startling visitant makes his appearance upon our midnight skies,--a great red star
that ... mounting higher with the deepening night,
blazes forth against the dark background of space with a splendor that outshines Sirius and rivals the giant Jupiter
himself. -- from Mars by Percival Lowell (1895)
Apr. 23, 1999:
Go outside about 2 hours after sunset and look toward the East. That
brilliant red star you see just above the horizon is Mars, and
it's headed our way.
There's nothing to worry about. Mars won't come any closer to Earth
than about 54 million miles, but this week and next Mars will be
brighter and nearer to Earth than at any time since 1990. It's a
great opportunity for amateurs to see details on the red planet through
a small telescope or to simply view Mars with the naked eye.
Right: This NASA Hubble Space Telescope view of the planet Mars is the
clearest picture ever taken from Earth, surpassed only by close-up
shots sent back by visiting space probes. The picture was taken on
February 25, 1995, when Mars was at a distance of approximately 65
million miles from Earth. The Red Planet will be even closer to
Earth during the coming weeks. more information
On April 24, Mars reaches "opposition," which means that it
passes through a point in its orbit that is
directly opposite the sun as seen from Earth.
At opposition Mars rises near sunset and is visible
all night from most latitudes. Shining at magnitude
-1.6, it will appear to be one of the brightest stars in the sky on
Saturday night. In fact, it will be as bright as Sirius
and second only to Venus in brilliance.
"This is a great time to view Mars with the naked eye," says Dr. John
Horack, a NASA astronomer. "By mid- to late-June the planet will be a full magnitude
dimmer, but for the next few weeks it will be
spectacular."
To find Mars
simply go outside any night for the next couple
of weeks about an hour or two after sunset.
Reddish colored Mars should be easy to spot 20 to 25 degrees above the
horizon in the east-southeast. Later in the evening,
near midnight,
Mars can be seen due South about 45 degrees above the horizon from mid-latitude sites in
the northern hemisphere.
Left: On April 24, 1999 when Mars reaches
opposition, the planet can be found in the constellation Virgo about 15 degrees
East of the blue-white star Spica (magnitude 1.2). This image shows Mars and Virgo viewed
about 40 degrees above the southern horizon at 11:30 p.m. local time on April 24.
If the orbits of Mars and Earth were perfectly circular then the
two planets would be closest together on April 24 at the exact
moment of opposition.
But that's not the case. Both planets follow slightly
elliptical paths around the Sun, so the instant of closest approach
doesn't arrive until May 1st when Mars will pass within 54 million miles of Earth.
By that time Mars will be slightly
dimmer than it was on April 24, but it will appear to be bigger
-- nearly 16 arcseconds across.
That's large enough to reveal details like the north
polar cap, dark surface markings and clouds
to amateurs
viewing the planet through a 6- to 8-inch telescope.
Sky & Telescope has prepared an excellent Mars Observing Guide
which reviews what can likely be seen on the red planet
through a telescope this month.
Martian oppositions occur about once every 26 months, but due
to the elliptical shape of planetary orbits not all oppositions are
the same. This year the apparent diameter of Mars will reach
16 arcseconds, the largest it's been in years, but in
2003 the disk will be a whopping 25 arcseconds across!
That's the maximum size Mars can ever be as seen from Earth.
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December 3: Mars Polar Lander nears touchdown  December 2: What next, Leonids? November 30: Polar Lander Mission Overview November 30: Learning how to make a clean sweep in space |
As Percival Lowell noted in his classic book Mars (1895), "no other heavenly body, Venus and the Moon alone excepted, ever approaches us so near..." and although the red planet "is neither new nor intrinsically great, he possesses for us an interest out of all proportion to his size or his relative importance in the universe." Lowell felt the enchantment of Mars to such a degree that he devoted his fortune and the latter part of his life to the study of its mysteries. Was it worth it? Is the allure of Mars really so powerful? For the next two weeks you can see for yourself.
The Planet Mars - from the SEDS Nine Planets web site
Life on Mars - A review of evidence of signs of life in the Allen Hills meteorite
Mars Global Surveyor - home page
Mars at opposition - 1995 images from the Hubble Space Telescope
Mars - by Percival Lowell, 1895
Related Stories:
Summer snow on Mars -- New Mars Global Surveyor images reveal snowy slopes. Mar. 25, 1999 NASA
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A new face on Mars has scientists smiling -- MGS beams back pictures of the "Happy Face Crater". Mar. 12, 1999 NASA
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Mars mapping begins in earnest -- MGS achieves its final orbit. Mar. 12, 1999 NASA
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A steamy cover-up on the red planet -- New evidence for active volcanism on Mars. Feb. 18, 1999 NASA
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The Sands of Mars -- Oct. 29, 1998 NASA
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New NASA images of the Martian North Pole -- Oct. 23, 1998 NASA
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New images of volcanoes on Mars and Io -- Oct. 14, 1998 NASA
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For more information, please contact: Dr. John M. Horack , Director of Science Communications |
Author: Dr. Tony Phillips Curator: Bryan Walls NASA Official: John M. Horack |