4 planets visible in the evening sky this week


Mercury, Venus, Mars and Saturn are all visible in the evening skies this week.

Mercury will be  the most difficult to see, being only about 20 degrees away from the Sun at the beginning of the week, and 23 degrees away from the Sun by end of week. However, it is a bright magnitude 0 object.
Venus will be the brightest at magnitude -4, and will be about 20 degrees away from Mercury throughout the week. Note that Mercury will be about halfway between Venus and the setting Sun.
Mars is about 12 degrees away from Venus, and easily found by noting its reddish color.
Saturn is close to Mars at 5 degrees away, with Mars closing in on Saturn as the days progress. By month’s end, they will be less than 2 degrees apart.

July 23rd, 2010, 9:00 PM MDT

July 23rd, 2010, 9:00 PM MDT

By finding these four planets, one can easily see the ecliptic plane, especially when extended to the Moon over in the southeast this week. The ecliptic is formally defined as the plane generated by Earth’s orbit, or as the path of the Sun across the sky. It is also known as the plane of the solar system, and all major planets and Earth’s Moon are found near the ecliptic.

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2 thoughts on “4 planets visible in the evening sky this week

  1. Only the Earth orbits directly on the ecliptic, as, by definition, Earth’s orbit is the ecliptic. All other planetary orbits are inclined slightly off the ecliptic.
    Mercury — 7 degrees
    Venus — 3.4
    Mars — 1.9
    Jupiter — 1.3
    Saturn — 2.5
    Uranus — 0.8
    Neptune — 1.8

    Thanks for your comment.

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