refractors , which show unwanted color around bright objects . Reflectors don ’ t have color and are more economical in comparable diameters but often display spikes of light ( most often , 2 , 4 , or 6 ), called diffraction spikes , from the “ spider ” assembly holding the secondary mirror . Sometimes these are distracting , often not . ( There are lots of other considerations in selecting a telescope , but that ’ s a whole article by itself .) A mount that automatically tracks the sky is very helpful when using high magnifications on planets . Earth ’ s rotation causes a magnified planet to pass through the field of view very quickly . To see the most , it ’ s important to be comfortable . Sitting comfortably at the eyepiece is best and standing comfortably is fine . Having to be in a contorted position to look through the telescope will shorten your session and distract from the concentration you want to give the view . If nearby lights glare into your peripheral vision , cover your head with a lightweight towel to shadow your face and the eyepiece from the offending lights .
When to Observe The geometric considerations of the opposition and closest approach of Mars drive the nights for observing over the long term . But the short term , time of night , is up to you , based on Mars ’ angular distance from the Sun . In general , your observations should be made when Mars ( or whatever !) is highest in the sky , called “ upper culmination ,” when the object crosses the “ meridian .” ( The meridian is the great circle on the sky cutting the sky in half from the south point on the horizon , through the zenith , to the north point on the horizon .) Upper culmination before opposition occurs after midnight , earlier and earlier ; after opposition it occurs before Sky ’ s Up
COURTESY OF NASA / Cory Huston A United Launch Alliance Atlas V rocket lifts off from Space Launch Complex 3 at Vandenberg Air Force Base in California carrying NASA ’ s Interior Exploration using Seismic Investigations , Geodesy and Heat Transport , or InSight , Mars lander on May 5 .
InSight to focus on interior of Mars
By STEPHEN EDBERG Guest Contributor
In a historic first , InSight made the first interplanetary launch , ever , from Vandenberg Air Force Base , on the Pacific Ocean west and north of Santa Barbara , Calif ., on May 5 . This is a holdover from its scheduled 2016 launch when Cape Canaveral was scheduled with other launches and too little time to ready the pad for InSight . A launch from Cape Canaveral gets more advantage from the Cape ’ s lower latitude . Launches from Vandenberg are limited to high inclination orbits ( to protect anyone on Earth ’ s surface from being hit by falling debris ). But as long as there is sufficient thrust available from the launch rocket and the upper stage sending the spacecraft on to Mars , the launch inclination is less important . You can follow InSight to Mars at https :// mars . nasa . gov / insight / and the links on it . Other ongoing NASA missions to Mars are covered at https :// mars . nasa . gov /. InSight ’ s landing on Nov . 26 is targeted for nearly the same Martian longitude as the landing sites of Viking 2 in north middle latitudes and the Mars Science Laboratory rover Curiosity . In fact , InSight is targeted for Elysium Planitia , just 373 miles ( 600 kilometers ) north of Gale Crater , where Curiosity landed . InSight is a lander , not a rover . It is designed to study the interior of Mars and the surface . A seismometer and a thermal heat flow probe , placed in a hole drilled into the surface , are highlights of its geophysical ( areophysical ?) payload during its prime mission intended to last one Martian year ( 708 Martian rotations [ called sols ] = 728 Earth days ). The two Viking Landers carried seismometers [ along with life detection laboratory instruments ] but they did not return Marsquake data after their landings in 1976 . InSight will place several scientific instruments on the Martian surface and scoop up samples for analysis by its internal laboratory instruments . Marsquakes may be generated by tectonic activity , volcanic eruptions , landslides and meteorite impacts . Whatever the source , they will provide information on the interior . Similarly , heat flow measurements characterize the behavior of the surface through the daynight cycle as well as provide information about the flow of heat from the core of the planet . After InSight arrives on Mars , you can expect good coverage of its results on websites associated with NASA ’ s Jet Propulsion Laboratory , NASA itself and the builders of InSight ’ s instruments . Look for links on https :// mars . nasa . gov / insight /. And don ’ t miss the ongoing exploration of Mars by orbiters and rovers — most with frequent releases of imaging data — at https :// mars . nasa . gov /.
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