Look, up in the sky! Moon Occults Mars, 2020-02-18

Occultation of Mars by the Moon, 2003-07-17.
Original photo © 2003 Andrew Chaikin.

On the morning of February 18th, 2020, observers in most of North America will be able to see the waning crescent Moon pass in front of (occult) the planet Mars.  The photo at the right, taken by Andrew Chaikin during the 2003 lunar occultation of Mars, is more dramatic than this event will appear through a telescope.  In the 2003 occultation, Mars was just 0.48 astronomical units (AU) from the Earth, while this time Mars will be at distance of 1.81 AU, 3.8 times farther away and correspondingly smaller and dimmer.  Still, Mars will shine at magnitude 1.2, one of the brightest “stars” in the sky, and its reddish hue will stand out against the colourless Moon.

Lunar occultation of Mars, 2020-02-18This map shows the visibility of the occultation.  The occultation will be visible in the area delimited by the cyan shape at the top and the multicoloured curve at the bottom.  The event will thus be visible in most of North America (except for Alaska and the far north of Canada), Central America, and the Caribbean.  In the area of the loop at the top left, covering part of the American northwest and western Canada, the Moon will rise with the occultation already in progress, but observers will be able to see Mars emerge from behind the Moon’s dark limb at its conclusion.

Because the Moon is relatively close to the Earth, there is substantial parallax affecting its apparent position in sky depending upon an observer’s location on the Earth.  Predictions for the occultation for 753 sites within the region of visibility are available from the International Occultation Timing Association Web site.  For each site, the time, and the altitude of the Sun and Moon are given for both disappearance and reappearance.  If the altitude of the Sun is negative, the event occurs before sunrise at that location.  Times are given in Universal Time (as appears in the header line of this site)—convert to your local time zone to plan observations.  The duration of the occultation depends upon your latitude; in most locations in the U.S. it will be around an hour and a half.  There is, of course, nothing to see while Mars is behind the Moon.  Observers on Mars would see the Moon transit part of the disc of the Earth.

For observers in the West, the disappearance (visible in some locations) and emergence will occur before dawn and can be observed with nothing fancier than the Mark I eyeball.  Further east, the occultation will take place in twilight or daytime skies.  While the Moon will, of course, be easily visible, to see Mars in daylight you’ll need a modest telescope, but since Mars will be so close to the Moon, there’s no difficulty finding it.

Here is the emergence of Mars from the occultation of 2008-05-10, photographed from New Delhi, India.  In that occultation, the emergence was from behind the illuminated limb of the Moon, while this time it will reappear behind the dark limb.

If you want to try photographing the occultation, the most spectacular photos are taken with the longest focal length that can be arranged (or with a camera attached to a telescope) that show the planet just before or after passing behind the Moon.  Observers in locations where the sky will be dark can video the event with any camera which allows zooming in so the Moon’s disc is clearly visible.  For video, remember to turn off auto-focus and manually focus at infinity: otherwise the camera is likely to “hunt” in focus, producing embarrassing and nausea-inducing blurring in the video.

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Author: John Walker

Founder of Ratburger.org, Autodesk, Inc., and Marinchip Systems. Author of The Hacker's Diet. Creator of www.fourmilab.ch.

10 thoughts on “Look, up in the sky! Moon Occults Mars, 2020-02-18”

  1. I didn’t realize “occult” could be used this way. I always think of seance and palm reading when I think of the word. The “oc-” is a prefix. It is from “ob-” but changes to “oc-” for pronunciation reasons.

    I think this is another example of a TRUMP ERA COVER-UP.

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  2. 10 Cents:
    I didn’t realize “occult” could be used this way. I always think of seance and palm reading when I think of the word. The “oc-” is a prefix. It is from “ob-” but changes to “oc-” for pronunciation reasons.

    I think this is another example of a TRUMP ERA COVER-UP.

    You always look on the dark side.

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  3. drlorentz:

    10 Cents:
    I didn’t realize “occult” could be used this way. I always think of seance and palm reading when I think of the word. The “oc-” is a prefix. It is from “ob-” but changes to “oc-” for pronunciation reasons.

    I think this is another example of a TRUMP ERA COVER-UP.

    You always look on the dark side.

    I am a man of principles and must call things the way I see it. I also want to get on MSNBC and CNN.

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  4. 10 Cents:
    How about those of us not in Norteamérica?

    If you’re in América del Sur, you’re in luck but elsewhere, no joy in 2020.  We’re in a Mars occultation season, where Mars’s orbit passes through that of the Moon, and there are five occultations of Mars this year, but apart from the one in February, all the rest are visible only from portions of South America.

    The ones visible from South America will be more favourable, with the 2020-10-03 event at Mars magnitude −2.5, which is brighter than any star in the sky.

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  5. John Walker:

    10 Cents:
    How about those of us not in Norteamérica?

    If you’re in América del Sur, you’re in luck but elsewhere, no joy in 2020.  We’re in a Mars occultation season, where Mars’s orbit passes through that of the Moon, and there are five occultations of Mars this year, but apart from the one in February, all the rest are visible only from portions of South America.

    The ones visible from South America will be more favourable, with the 2020-10-03 event at Mars magnitude −2.5, which is brighter than any star in the sky.

    Can’t you make it Japón?

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  6. 10 Cents:
    Can’t you make it Japón?

    There is an occultation of Venus on 2020-12-12, when Venus will be at magnitude −3.9 (spectacularly bright) which will be visible from northeast Asia.  It looks to me like it just clips the very northernmost part of Japan.

    Occultation of Venus 2020-12-12

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  7. 10 Cents:
    I didn’t realize “occult” could be used this way. I always think of seance and palm reading when I think of the word. The “oc-” is a prefix. It is from “ob-” but changes to “oc-” for pronunciation reasons.

    I think this is another example of a TRUMP ERA COVER-UP.

    The verb “occult” means “to hide or obscure.”

    As you are pretty obscure yourself, I figured you would know that.

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  8. Not long after Mars emerged from its occultation by the Moon, Paul Schmit and Gary Schmit photographed the Moon, Mars, and the International Space Station (ISS) passing in front of the Moon all in a single frame from their observing site in New Mexico in the United States.  It was 06:25 local time, as the sky was brightening, but the ISS, at an altitude of 400 km, was in full sunlight.  The transit of the ISS across the Moon took about a second.  Click the image to enlarge.  Mars is the reddish dot at around the two o’clock position with respect to the Moon.

    ISS transits the Moon shortly after the Moon occults Mars, 2020-02-18

    This was the Astronomy Picture of the Day for 2020-02-20.

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