Mercury

Five planets arc across our skies this month but you have to get up early to see them

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The positions of the five naked-eye planets and Moon are shown here as they will appear before dawn on June 20, 2022. Image via SkySafari 6 Pro.

It has been 18 years since Earthlings have been able to spy five planets in their skies, together and in order from Sun outward, but it’s possible now through the end of June. Want to take a look? Maybe you should. Yes, get up early — 30 to 45 minutes ahead of sunrise — find a spot where you can see the southern sky, and sweep your gaze from the east to the south.

Given clear skies low to the eastern horizon, look for a tiny star-like dot. If you’re lucky, you’ll have spotted planet Mercury, the most elusive of the worlds you’ll see due to its size and proximity to Sun. Moving westward, next comes Venus. You’ll have no trouble spotting Earth’s overheated sister as it will shine brilliantly even in early twilight.

Skipping Earth (it doesn’t count because you’re standing on it) Mars is next in line. Look for a little reddish light not far from brighter Jupiter. Moving across a bigger gap and looking south, we finally reach Saturn, the Lord of the Rings. The ringed world will appear as a slightly golden star.

Looking “down” on the Solar System, this diagram shows the field of view from Earth as it takes in the five naked-eye planets — the Solar System as it was known before the invention of the telescope. Image created via SkySafari Pro 6.

Binoculars will help, especially in finding tiny Mercury, but may also allow users to see Jupiter’s four Galilean Moons. A little visual aid may also help in confirming it’s Saturn that has been spotted — if the rings aren’t distinct, the planet will appear as a bright oval and not like a starry speck.

The planets will be joined by Earth’s Moon at various points along their arc, changing placement nightly from about June 18 — 28. A beautiful arrangement will occur on June 24 when the then-crescent Moon will float between Venus and Mars. Around the 28th, Moon will have drifted out of the arc entering its New (dark) phase.

The planets of our Solar System may appear to be close together at times when we see them from Earth but they’re not. Nor will their combined gravitational pull have any effect on Earth. Relax and enjoy the show! Image created via SkySafari 6 Pro.

At the end of June, Mercury will slip too close to Sun for it to be seen by casual observers, ending the celestial gathering. The four other planets, however, will remain in their arc though their relative positions will shift nightly and almost imperceptibly, until they no longer form a visual chain.

The five-planet dance was last seen in 2004 and it won’t happen again until 2040. Maybe you’ll be on your way to or from work. Perhaps the dog needs walking. You may even think it’s worth getting out of bed early on a clear, cool June morning so you can tell everyone you saw five planets all together. Whatever puts you under a clear starry sky, look up and enjoy our wonderful universe.

2016: Our brief transit of Mercury

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Photo: 2016 Transit of Mercury. Photo by James Guilford.
Mercury’s Transit in Progress: Mercury is the tiny dot at the lower-left. Smudge near the center is a group of sunspots. Photo by James Guilford.

Our Solar System doesn’t care about the local weather. When something rare and interesting like today’s transit of Mercury across the solar disk takes place, it happens and there are no “rain checks.” And so it was this morning when the day dawned clear to partly-cloudy allowing us to glimpse the beginning of Mercury’s trek only to have the show stopped by rapidly encroaching clouds progressing to solid overcast!

Photo: Transit of Mercury blocked by clouds. Photo by James Guilford.
Transit of Mercury: Mother Earth’s atmospherics begin to block the view! Photo by James Guilford.

At the predicted hour Mercury appeared as a tiny dot, silhouetted in the lower left-hand quadrant of the Sun’s bright disk. Using special protective filters, observers on the ground watched as the small dot slowly moved inward from Sol’s limb. Here in Northern Ohio, transit watchers were treated to the beginning of the show. Much of the nation missed out entirely, cloud cover already in place at dawn!

Photo: GOES weather image, May 9, 2016.
Weather Satellite Image: Much of the US cloud-covered during the transit event.

NASA’s Solar Dynamics Observatory, a spacecraft, is unaffected by Earth’s pesky atmospherics and its technology produces some very dramatic images. One of my favorites shows Mercury about to cross between the satellite (us) and the Sun’s glowing photosphere; the planet has the active solar atmosphere as backdrop. Planet Mercury is 3,030 miles in diameter, not much bigger than Earth’s Moon, and looked every bit as tiny as it is compared with our nearest star!

Photo: Mercury's transit about to begin. Data courtesy of NASA/SDO, HMI, and AIA science teams.
The View from Space. Credit: Data courtesy of NASA/SDO, HMI, and AIA science teams.

Today’s transit of Mercury took place over several hours. For us in Northern Ohio, the transit began at about 7:12 AM Eastern Daylight Time with the Sun barely up. Midpoint of Mercury’s passage was at 10:57 AM, and the transit ended at 2:42 PM. Because of the orbital inclinations of the inner planets, the alignment needed to produce a transit of Mercury happens only about 13 times per century making even a glimpse of the event something special. After today’s, the next transits of Mercury will take place in November 2019, November 2032, and November 2049.

At least we won’t have to wait for so long as we must for the next transit of Venus — that happens in December 2117.

 

May 9: Mercury crosses the Sun

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On Monday, May 9 solar observers in North America will be able to see the silhouette of planet Mercury as it passes between Earth and our Sun. The event, called a transit, is relatively rare — though not so rare as a transit of Venus — and may cause interest in viewing the Sun. WARNING: Looking at the Sun, especially through optical instruments, requires extreme caution! Permanent vision damage can result if proper precautions are not taken! Click here for a good article on safely observing the Sun.

At present we DO NOT plan to open Stephens Observatory for the transit but if plans change, the announcement will be made here — check back later. If conditions are clear, we hope to post images made via telescope at a remote location.

Tiny planet Mercury will appear as a correspondingly tiny black dot against the Sun’s brilliant disk. If any sunspots are present on Sol’s face, compare them with Mercury: the planet will be distinctly round and noticeably darker than sunspots, and from minute to minute it will move — sunspot motion takes days!

Image: Planetary positions on May 9, 2016.
May 9 Transit of Mercury – Note how the orbits of Mercury, Venus, and Earth are “tilted” making line-of-sight alignment a rare occurrence.

Viewed from Earth, transits occur when one of the inner planets crosses the line of sight between our world and the Sun; only Venus and Mercury are ever able to do that. A transit, then, is a bit like a solar eclipse only viewed at a greater distance and blocking only a small amount of the Sun’s light.

Transits would occur more often but for the fact that the orbits of Mercury and Venus are “tipped” so that they do not align along the same plane as Earth’s path. Only when the planets are in the right position where the line of sight passes straight through to the Sun do we see transits and with Mercury, that happens only about 13 times per century. After May 9, the next transits of Mercury will take place in November 2019, November 2032, and November 2049. The most recent transit of Venus took place in June 2012 and will not be seen again until December 2117.

Monday’s transit of Mercury will take place over several hours. For us in Northern Ohio, the transit begins at about 7:12 AM Eastern Daylight Time with the Sun low in the east. Midpoint of Mercury’s passage will be at 10:57 AM, and the transit ends at 2:42 PM.

Cloudy skies? Don’t have proper gear to view the Sun? Fret not! There will be “live” webcasts of the event from various sources during Mercury’s passage. Use your favorite web search engine to find good sources and check for a planned broadcast via NASA TV. NASA will stream a live program on NASA TV and the agency’s Facebook page from 10:30 to 11:30 AM — an informal roundtable during which experts representing planetary, heliophysics and astrophysics will discuss the science behind the Mercury transit. Viewers can ask questions via Facebook and Twitter using #AskNASA.

We hope to post a few links here later.

More planets line up in our morning sky

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Illustration: January 2016: Five Planets Visible in the Pre-Dawn Sky
January 2016: Five Planets Visible in the Pre-Dawn Sky

 

Over recent weeks we have watched as several planets have appeared close together in our morning sky — when clear, that is — and even seen them shift their positions as the days passed! Beginning this frigid week and continuing into mid-February, five of Earth’s Solar System siblings will be visible, spanning the southern sky. This is the first time since 2005 that this planetary lineup has occurred. If we get a break in morning cloud cover go out, just before dawn’s early light, and look for the planetary parade. Little Mercury will be the hardest to spot being both dim and close to the horizon. Venus and Jupiter will be easy as they are the brightest of the bunch. Golden Saturn and finally reddish Mars should also be easy to find though Mars isn’t a standout. The gathering will occur again late this summer and in the evening sky. The planets aren’t really very much closer together in space during this time. The chart below illustrates the current relative positions of the planets; it’s our point of view from Earth that makes creates the scene: something like watching racers on a race track, appearing closer and farther apart as they run laps in their concentric lanes.

Illustration: January 2016: Planetary Positions - Area Between Lines of Sight Illustrates Area of Space We See
January 2016: Planetary Positions – Area Between Lines of Sight Illustrates Area of Space We See