[Energetic music]
[Preston Dyches] What's Up for April?
Mercury rising,
this month's Moon and planet pairings
and the Lyrid meteor shower.
First up, on April 11th, the planet Mercury, smallest
and fastest moving of the planets
in our solar system,
will reach its highest and most visible
in the evening sky for the year.
Mercury is only visible in the sky
for a few weeks every three to four months.
The rest of the time it's too close to the sun in the sky
and is lost in its bright glare.
And since the planet orbits so close to the sun,
it's always near the sun in the sky.
Appearing low near the horizon for no more than an hour or two,
either following sunset or preceding sunrise.
Some of Mercury's fleeting appearances,
known as “apparitions,”
are better for observing than others,
for a combination of reasons that have to do with
how our view of the solar system changes with the seasons,
what hemisphere you're in, and what phase
the planet happens to be showing us at the time.
For this apparition, in the Northern Hemisphere,
the best viewing is April 3rd through the 11th,
as the planet appears higher in the sky each evening.
It quickly fades in brightness after that, as the phase
it shows us becomes an increasingly slimmer crescent.
Also on April 11th, you'll find the planet
Venus right next to the Pleiades star cluster.
The two will be close enough to appear
in the same field of view through binoculars.
This pairing makes for a fun reminder that the night sky
is kind of like a time machine.
The farther out in space you look, the farther back in
time you're seeing.
On that night you're seeing light that left Venus about
nine minutes earlier,
whereas the light of the Pleiades left
those stars around 400 years ago.
The latter half of April
includes some awesome close approaches of the Moon
with three of the bright planets in the sky.
On April 15th and 16th, you'll find the crescent Moon
rising with Saturn.
Find them low in the southeastern sky
in the couple of hours before sunrise.
Then on the evening of the 23rd, find the slim crescent Moon
hanging just five degrees above Venus in the west after sunset.
And on April 25th, the Moon finds its way over
to Mars high up in the west after dark.
At this time, around the 26th and 27th,
the Moon will be at its first quarter phase, meaning
it appears as a “half-moon,” high in the sky after dark.
The first-quarter Moon is a great time
to pull out your binoculars or telescope if you have them,
as it's an ideal time to observe the Moon's
craters and mountains along the terminator,
the day/night boundary, with ease.
Lots of astronomy clubs plan
public observing nights around this time as well,
and you can look for events in your area
with NASA's Night Sky Network.
April brings the annual Lyrid meteor shower.
It's a medium-strength shower that can produce up to 20
meteors per hour at its peak, under ideal conditions.
The Lyrids peak this year in the pre-dawn hours of April
23rd, though,
you should see a few shooting stars
on the morning before and after the peak as well.
Fortunately, the peak falls
just a couple of days after the new moon.
That means the Moon won't interfere
with this year's Lyrids
overwhelming fainter meteors in the glow of moonlight.
The Lyrids are named for the constellation Lyra,
which is near the point in the sky where their meteors
appear to come from, called the radiant.
They're one of the oldest known meteor showers,
with a first recorded sighting in China some 2,700 years ago.
They originate as dust particles from a comet
during its 400-year orbit around the Sun.
The Lyrids tend to produce fast-moving meteors
that lack persistent trails,
but they can also produce
the occasional bright meteor called a fireball.
To observe them,
find a comfortable spot away from bright city lights,
get horizontal and look straight up.
You'll see the most meteors by looking slightly away
from the origin point, which is near the bright star Vega.
So here's wishing you clear skies to catch a few
shooting stars one April morning when the forecast calls
for light showers of comet dust with a chance of fireballs.
Here are the phases of the Moon for April.
Stay up to date with all of NASA's missions
to explore the solar system and beyond at nasa.gov.
I'm Preston Dyches from NASA's Jet Propulsion Laboratory
and that's What's Up for this month.