There is no question which is the most prominent planet this month. It's certainly none other than dazzling Venus, which rules the western evening sky this month, offering spectacular views as it reaches its greatest brightness of the year.
Over a 30-day time span, the bright "evening star" will:
- Skim the Pleiades star cluster
- Shine at its brightest
- Present a long and narrowing crescent in telescopes
- Stay up well past its normal viewing time after sunset, and
- Team up with a lovely crescent moon.
Let's go point by point through our list.
Venus "kisses" the Seven Sisters
Venus will appear dramatically close to the Pleiades during the first several evenings of April. On April 1, we can see it hovering just below this beautiful open cluster of stars, known colloquially, as "The Seven Sisters."
On the evening of April 3, Venus is just one-quarter of a degree southeast of Alcyone, the brightest star in the cluster, and one-third of a degree south of the neighboring stars Atlas and Pleione. Venus is only about three-quarters of a degree from the cluster's center on the night before and a little over 1 degree the night after.
Venus's glare will practically overwhelm the cluster for naked-eye observers when it is closest, but binoculars and wide-field telescopes will show both the planet and the cluster beautifully. Only once every 8 years can Venus come so near the Pleiades — and in our lifetime these conjunctions (or close encounters) have been getting ever closer. As Venus continues to pass a little farther north, it will actually go right through the main Pleiades stars in the years 2028, 2036, 2044 and 2052.
The pinnacle of brilliance
Venus starts April at magnitude -4.5 (magnitude is a measurement of brightness used by astronomers, with lower numbers denoting brighter objects. Negative numbers denote exceptionally bright objects.) On April 27, the planet reaches a magnitude of -4.7, the brightest it will become this year, also referred to as its "greatest illuminated extent." — a compromise between its increasing apparent size and the diminishing illuminated portion of its disk.
On this date Venus will appear to shine more than nine times brighter than its nearest planetary competitor (Jupiter) and will outshine Sirius, the brightest of all stars, by more than 20-fold. In dark locations free of significant light pollution, the planet's light is bright enough to cast faint but distinct shadows. And if you know precisely where it is, you'll be able to see it in the daytime: a tiny white speck against the blue background sky.
An increasingly large, narrowing crescent
Telescopes will show Venus's apparent diameter noticeably increasing in April while its phase thins from 47% to 25% lit. If you hope to see any subtle detail in Venus's clouds, observe before the sky gets too dark and Venus dazzles with glare.
As we have just alluded to, this is an ideal month to view the crescent of Venus in broad daylight through binoculars, a telescope — or even (if you have exceptional vision) with your naked eyes.
Related: Examining the phases of Venus
Staying up late
In not a few astronomy guidebooks, you'll read that Venus always remains close to the sun's vicinity, setting within a few hours of the sun and is never visible at midnight. But this month, for viewers living in mid-northern latitudes from April 7 through April 22, Venus will be setting unusually late; after 11:30 p.m. local time.
However, it should be noted that we provide local mean time (LMT) of rise and set times, not their civil time. Our civil time zones are standardized on particular longitudes. Examples in North America are Eastern, 75 degrees west; Central, 90 degrees; Mountain, 105 degrees; Pacific, 120 degrees. If your longitude is very close to one of these (as is true for Philadelphia, New Orleans and Denver), luck is with you and this correction is zero. Otherwise, to get standard time you'll need to add 4 minutes for each degree of longitude that you are west of your time zone meridian, or subtract 4 minutes for each degree you are east.
Thus, for a place like Boston, which is about 4 degrees east of the Eastern standard meridian, you'll need to subtract 16 minutes. So Venus will actually set before 11:30 p.m. during that April 7-22 time frame. On the other hand, Indianapolis, is 11 degrees west of the Eastern standard meridian, so you'll need to add 44 minutes. So in reality, as seen from the city nicknamed the "Crossroads of America," Venus will appear to set after midnight; as late as 12:18 a.m. on April 15!
Of course, another factor is that much of the country (save for Arizona and Hawaii) is also currently on daylight saving time. And that is the primary reason why the "goddess of love" stays up unusually late this month. If, for example, we were still observing standard time, then from Indianapolis Venus would set at 11:18 p.m. on April 14.
A final evening celestial tableau
Although they are widely separated by 7 degrees, the two brightest objects in the night sky — the moon and Venus — still make for an eye-catching sight as they descend side-by-side in the April 26 west-northwest sky; their final readily visible evening encounter before Venus transitions into the morning sky in early June.
Editor's note: If you have an amazing skywatching photo you'd like to share for a possible story or image gallery, you can send images and comments in to email@example.com.
- The brightest planets in April's night sky: How to see them (and when)
- What is a 'morning star,' and what is an 'evening star'?
- The 10 weirdest facts about Venus
Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for Natural History magazine, the Farmers' Almanac and other publications. Follow us on Twitter @Spacedotcom and on Facebook.
All About Space magazine takes you on an awe-inspiring journey through our solar system and beyond, from the amazing technology and spacecraft that enables humanity to venture into orbit, to the complexities of space science.