Spot Mars in the Sky!
There is an element of timing involved in stargazing. The Earth’s motion around the Sun gives an ever-changing vista on the fixed stars through the seasons. The planets progress, each at its own rate, providing a changing lineup of conjunctions, oppositions, and sometimes brief windows of especially good visibility.
For Mars, the opportunity comes every 26 months, when Earth passes within about 60 million miles of its neighbor. Mars opposition is when Mars is directly across from the Sun from our perspective. When in opposition Mars will rise at sunset and be visible all night, setting at sunrise. Since the orbits of Earth and Mars are not perfectly circular, the distance varies depending on the time of year at which the lineup occurs. At a particularly good opposition, like the one in 2003, we’re within 35 million miles of Mars. In July 2018 it was just over 35 million miles, but the alignment was low in our Michigan sky, and the telescopic image of Mars wavered in a thick column of summer atmosphere — the surface of the planet further obscured by a planet-wide dust storm. This month, we’re not quite as close to Mars as we were two years ago — about 39 million miles — but the fact of the alignment happening in autumn means Mars is higher in our sky than the last time around. That means less turbulent air to look through, and so far the weather (on Mars) is cooperating too.
These near passes with our rusty desert neighbor also provide another kind of opportunity. They are the best time for a spacecraft visit, the distance between the two worlds being the shortest. The Viking missions, Mars Pathfinder, Spirit and Opportunity, Mars Reconnaissance Orbiter, Curiosity, InSight, and others, all launched for Mars in the months leading up to an opposition event. This year it is the Rover Perseverance and its companion, Mars Helicopter Ingenuity, launched July 30, that are now cruising toward Mars for a scheduled powered landing at Jezero Crater in February.
This new Mars mission improves upon those of the past. Built around the successful structure of the Curiosity Rover, and with a similar but improved powered landing system, Perseverance hosts the current generation of new and improved scientific instruments. These include 23 specialized cameras, microphones to listen to the Martian environment, a ground penetrating radar system, and a core sampling mechanism for collecting samples of the crust for return to Earth by a future mission. Perseverance will also be the first mission to conduct experiments specific to an eventual human presence on Mars, including one to produce oxygen from the Martian atmosphere, and one that tests potential space suit materials. The experiment that most sets this rover apart from its predecessors though must be the Mars Helicopter Ingenuity. If successful, this drone will act as a scout for the rover and pave the way for a new mode of exploring alien worlds.
Want to see Mars in the sky? It will be hard to miss. Rising in the hour around dusk, with best viewing between about 11 p.m. and 5 a.m. Mars will climb above 50 degrees in altitude to the south, the brightest point of light in the sky until Venus comes up just before sunrise (it will just edge out Jupiter in brightness). Mars is noticeably amber to reddish in color. One factor that could interfere is smoke from the fires out west, but the brightness of Mars will work in our favor, even if there is a little haze to look through.
If you have access to a telescope, then this opposition will be your best opportunity to glimpse Mars’ south polar ice cap and the visible contrast of its highlands and lowlands. Patience at the eyepiece pays off especially with Mars as the longer you allow for the image to integrate in your vision, the more details you will see. One useful trick toward seeing more detail is to draw while you observe. This also leaves you with a keepsake to show others at the end of the session.
Weather permitting, public nights on October 17 and 24 will be held at the Veen Observatory this month. Visit graaa.org for all details.
Happy stargazing.
By: John Foerch, Planetarium Production Programmer for the GRPM’s Roger B. Chaffee Planetarium.