Sunday night, January 20, will bring the first celestial spectacle of 2019 to sky watchers across the Americas: a total eclipse of the moon. This promises to deliver a deeply reddled eclipsed moon and an extensive wholeness. As a bonus, the whole will begin before midnight in the continental US and Canada, and Monday is a holiday for many school-aged kids who like to stay up late and watch the entire event.
The next visible total lunar eclipse of North America will occur in May 2022 – but half of the country will miss the beginning of that. We will not see another total lunar eclipse visible from coast to coast in North America until March 2025, so let's make the most of this!
Your favorite mobile astronomy app can help you plan the big event. It will tell you when the eclipse will begin and end at its location where the eclipsed moon will be in the sky (which is especially useful if you want to photograph the event), and where to look for some of the objects that will be revealed when the moon is completely darkened . [Super Blood Moon Lunar Eclipse of 2019: Complete Guide]
Understanding Lunar Eclipse
Because the Earth is a solid sphere with the sunlight shining on it, our planet casts a circular shadow in the space opposite the sun. Of course, the black shadow is invisible on the black background of space. But if an object, such as the International Space Station or the Moon, passes through this shadow, the Earth will prevent direct sunlight from reaching the object, darkening it. If you observe the passage of satellites on a dark and clear night and observe where in the sky they disappear (let the sunlight) or suddenly appear (in the light of the sun), you can trace the shadow of the Earth. It's always there!
The region of space where Earth completely blocks sunlight is called an umbra (from which comes the word "umbrella", a shade of the sun). Around this, there is a much larger, but less dark circular zone, called penumbra. For objects passing through the gloom, a portion of the sun is always visible, so that these objects receive partial sunlight and appear darkened, but still visible, from the Earth.
Lunar eclipses occur when the constant movement of the moon in orbit around Earth takes the natural satellite east through the penumbra or the umbra. If the moon completely enters the umbra, we see a total lunar eclipse. If part of the moon remains in the penumbra, we see a partial lunar eclipse. Either way, lunar eclipses are 100% safe to view with unprotected eyes – both directly and through binoculars. A telescope can reveal the shadow of the Earth crawling across the surface of the moon in real time.
And the "blood moon"? Part of the sunlight that flows near the Earth passes through our atmosphere. The air refracts (or bends) the sun's rays by slightly lessening the light. Refraction allows sunlight to curve around the Earth's horizon, making a moon eclipsed reddish with the colored light of the sun, hence the blood moon's nickname for eclipsed moons. If you could see the Earth from the surface of the moon during a total lunar eclipse, you would see our dark globe surrounded by a beautiful halo of reddish light!
When will the eclipse happen?
With astronomical applications like SkySafari 6 for Android and iOS, Stellarium Mobile and Star Walk 2, you can view each stage of this lunar eclipse by configuring the application for the corresponding times mentioned below.
The partial phase of the lunar eclipse will begin when the Moon comes into contact with the Earth's umbra, at 0334 GMT on Monday morning, January 21, or at 22:34 in the morning. EST and 7:34 PM PST on Sunday night (January 20) in North America. (GMT, or Greenwich Mean Time, is usually expressed as Universal Time, or UT, by astronomers.) From that moment, look for the darkness that grows along the lower left edge of the moon. The SkySafari application also shows the phases of the twilight of the eclipse, so you will notice the moon darken from 0236 GMT (9:36 p.m. on January 20 EST).
Beginning at 0441 GMT, or 11:41 pm on January 20, the Moon will be entirely within Earth's umbra. Our natural satellite will pass through this shade, extending the totality to 62 minutes and darkening much more the southern half of the moon than the northern half. The total eclipse phase will end when the moon leaves the umbra at 0543 GMT, or at 0943 EST on Sunday. The partial eclipse phase will end at 06:51 UT, or 1:51 EST.
In the largest eclipse, which will occur at 5:13 a.m., the very dark reddish moon will be in the width of the palm to the right (or west) of a large open star cluster known as Beehive (and Messier 44) in Cancer, the crab. Without the bright moonlight dominating this cluster, you can easily see your stars in binoculars. [Amazing Photos of the Rare Supermoon Total Lunar Eclipse]
Finding the eclipsed moon
For a total solar eclipse, you can see the event only if it is parked along the narrow path that the moon's shadow travels along the Earth. By contrast, a total lunar eclipse is visible to all on Earth, for whom the moon is above the horizon, while the moon crosses the shadow of the Earth. The lunar eclipse of this weekend will be visible in North and South America, the eastern Pacific Ocean and the westernmost part of Europe. Much of the eclipse will be visible in central and eastern Europe, but observers will miss the last stages of the eclipse because they will occur after the moon. For the western Pacific region, the moon will rise after the eclipse begins.
The moon's position eclipsed in the sky depends on its location: The moon may be low in the east if the eclipse is occurring as the moon rises, high in the southern sky, or it may be low in the west if the eclipse is occurring soon before the moon sets where you live. And since the whole eclipse will last more than 3 hours, the height and direction of the moon will change from beginning to end.
Your astronomy application can show where the moon will be in each phase of the eclipse. This is useful for planning where to gather everyone to your viewing team and avoid the need to move in the middle of the eclipse if the moon moves behind a building or tree. It is also advisable to check the Moon's trajectory if you plan to mount a camera on a tripod and capture a time-lapse video or a series of framed still photos in some beautiful scenery in the foreground. See what to do.
Take your smartphone or tablet out and set the date and time for the time interval in which the eclipse will occur in your location. In SkySafari 6, the easiest way to do this is to find the moon in the application (by touching the moon on the display or by using the Search menu) and then invoke the object information for the moon by tapping the selection icon on the bar tools. In the Lunar Phases section of the page, you will find clock icons next to each future phase of the moon. Tap the clock icon of the next Full Moon entry, and the application will advance to display the eclipsed moon on the correct date and time. (The application displays the next full moon. If you exceed in February, simply open the time flow controls and set the date to before January 20, 2019.)
While the eclipsed moon is displayed, activate the compass mode of the application and hold your device against the sky, moving the phone until the eclipsed moon appears on the display. The direction and the time you are holding the device will show where the moon will be during the eclipse. (If you can not find the moon, try to calibrate the compass of your device or push the display to show more of the sky.)
Now that you know where in heaven the totally eclipsed moon will be, you can walk around and decide where to ride. If you have selected the maximum eclipse time, the totality will cover an hour centered at that time. Before finalizing your decision, use the application's time settings to return to the beginning of the partial eclipse (about 1 hour and 45 minutes before the maximum eclipse) and observe the position of the moon at that time. If you repeat the exercise to the end of the partial eclipse (about 1 hour and 45 minutes after the maximum), you will see the full area of the sky covered by the event.
Some news agencies are extolling that this eclipse will happen as the moon approaches the perigee, its closest approach to Earth during the month, commonly called the super moon. But it really works against us. Supermoons are slightly larger than average and travel a little faster in their orbit (due to the laws of Kepler's motion). Therefore, this moon will spend less time completely eclipsed than it would have if it were further away. If you want to play an earlier lunar eclipse, set your app to 0748 GMT on April 15, 2014. This translates to the hours before dawn. Find a complete list of past and future eclipses on NASA's eclipse pages here.
Finding Light Skies
I have a friend who is known for loading his car with cameras and telescopes and driving up to where he will have a perfectly clear sky for a lunar eclipse. He once traveled from Toronto to a small town west of Chicago – arriving just in time to photograph the entire event with beautiful colors!
My favorite app to predict the clear skies preferred by astronomers is Astrospheric for iOS and Android. This app also has a version of the web browser. When you start the application, it will use your current location to summon a 48-hour forecast that includes the amount of cloud coverage, air transparency, and air stability (which astronomers call the "view") displayed as a row of colors. coded boxes that indicate the weather conditions every hour. Touching a box at a specific time updates a regional cloud cover map on the top half of the screen. You can change the map to show a variety of parameters, including light pollution.
The application also displays hourly data for wind, temperature and humidity, as well as charts for rising and setting the sun and moon. Scrolling up the screen reveals a shortened version of the weather for the next seven days, a list of the current and future phases of the moon and a map showing where the prediction is valid. If you sign up for a free account, you can save more than one location, allowing you to summon the forecast to your favorite cottage or site.
I have found that the Astrospheric predictions are very reliable. Another recommended weather forecast for astronomers is Clear Outside for iOS and Android. This application also offers a browser version of the Web and provides information similar to the Astrospheric, including a division of the expected type of clouds – high, medium, low and total percentage – and predictions for when the International Space Station passes.
Let's hope for clear skies for everyone this coming Sunday night. My fingers are crossed, but if you're cloudy, be sure to tune in to one of the live eclipse broadcasts offered by Griffith Observatory, Timeanddate.com, Slooh.com and others. And do not forget to share your eclipse photos with Space.com.
Future Mobile Astronomy columns will feature previews for more of the 2019 celestial events, discuss how to recreate the Apollo missions 50 years later, explore how to measure star distances, and more. Meanwhile, keep looking up!
Editor's note: If you take an amazing photo of the total lunar eclipse of January 2019 that you would like to share with Space.com and our news partners for a possible story or image gallery, send comments and images to: [email protected]
Chris Vaughan is a specialist in astronomy and public education at AstroGeo, a member of the Royal Astronomical Society of Canada, and operator of the landmark David Dunlap Observatory 74-inch (1.88 meter) telescope. You can contact him via email and follow him on Twitter. @astrogeoguy, as well as on Facebook and Tumblr.