Mercury at East Elongation

Click on graphic to see it full size.

Click on graphic to see it full size.

   Mercury reaches a point in its orbit called greatest eastern elongation. As this graphic shows the inner planet Mercury is more or less at a right angle (90o) from the Sun and Earth. From the surface of the Earth, your backyard, for example, Mercury is to the left, or eastern side of the Sun and is setting after the Sun.
mercury-orbit-ani   At eastern elongation Mercury, or for that matter Venus the other inner planet, are as far out from the Sun as we see them and as a result Mercury or Venus will set at the latest time in this orbit. From eastern elongation forward Mercury or Venus will be setting earlier each evening as the planet is moving in retrograde, westward, toward the Sun and inferior conjunction. With luck and a clear horizon the very thin waxing crescent Moon, approximately 30 or so hours old, may be just visible to the right from Mercury.

   
   
   
Caution: Objects viewed with an optical aid are further than they appear.
   Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

Mercury at Superior Conjunction

mercury-ani   Today or late last night depending on your time zone at 6 UT (Midnight CST) the innermost planet Mercury reached what is called superior conjunction. at this position the planet Mercury is on the opposite side of the Sun from the Earth. From superior conjunction the planet Mercury will continue moving eastward and will become visible as an evening planet during January.

   
   
   
Caution: Objects viewed with an optical aid are further than they appear.
   Click here to go to the Qué tal in the Current Skies web site for more observing information for this month.

Mercury Behind the Sun

19-31 August

19 to 31 August

   Today the innermost planet Mercury reaches the point along its orbit around the Sun where it is on the opposite side of the Sun from the Earth. This position is referred to as superior conjunction and all solar system objects orbiting the Sun will, at some point in their respective orbit, reach superior conjunction.
Click on image to see it full size

Click on image to see it full size

   Each frame of this animated graphic shows the planet Mercury at one-day intervals as the planet moves behind the Sun. We see Mercury from this perspective rather than as it is shown in the banner graphic at the top of the page. This is because the Earth and the other 7 planets all orbit the Sun on pretty much the same plane, or level.

   
   
   Click here to go to the Qué tal in the Current Skies web site for more observing information.

Mercury Goes to Extremes

   mercury-aniToday the innermost planet Mercury reaches a point along its orbit around the Sun where it is more or less at a right angle from the Earth and the Sun, as the banner graphic at the top of the page shows. As viewed from above Mercury is to the right from the Sun, while from the backyard view on the Earth’s surface Mercury is also to the right from the Sun, or on its west side. This puts Mercury in the morning skies rising before the Sun rises and leading the Sun across the sky from east to west as the Earth rotates from west to east.

Earth, Inner Planets, and the Ecliptic

Earth, Inner Planets, and the Ecliptic

   From our backyard perspective we view the planets at more or less the same level because the 8 planets orbit the Sun on or close to the plane of the ecliptic, the Earth’s orbit extended outward from the Sun. So from this perspective the two inner planets appear to move back and forth, left to right to left, as they orbit the Sun. Today Mercury is at the ‘turning point’ on the right side of the Sun, which places Mercury at its greatest western elongation, or at its maximum angular separation from the Sun as seen from Earth. Today Mercury is approximately 20 degrees from the Sun. Due to its closeness to the Sun Mercury never gets more than around 30 or so degrees from the Sun which means that Mercury never rises or sets more than about 2 hours from the Sun. (The Earth rotates approximately 15 degrees every hour)

Click here to learn a little (or a lot) about the innermost planet Mercury from two MESSENGER web sites.

30 July - 5:30 am CDT

30 July – 5:30 am CDT

   While out observing Mercury look a little higher to the right for the planets Mars and Jupiter, plus some of the stars of the northern hemisphere winter season. While these two outer planets are also to the west from the Sun they do not have an elongation position as outer planets orbit the Sun beyond the Earth’s orbit rather than between the Earth and the Sun. Outer planets do reach a 90 degree angle relative to the Earth and the Sun but it is known as either east or west quadrature.

30 seconds worth of Mercury from the Orbit performance.

   
   Click here to go to the Qué tal in the Current Skies web site for more observing information.

Moon – Venus Conjunction

Moon Venus Conjunction

Monday morning watch for the thin waning crescent Moon to be close to the very bright planet Venus. Up to the right is Jupiter and if you have a clear and relatively flat eastern horizon you may even catch a glimpse of the other inner planet, Mercury.

Be sure to visit Qué tal for more observing information.