[Lively music]
What's Up for April?
Conjunction junction
and a hidden surprise in the Big Dipper.
At the beginning of April, Venus, Mars and Saturn
form a trio in the southeast before sunrise, with Saturn
appearing to move steadily toward Mars each day.
On April 1st, they're a couple of finger widths apart.
And by the fourth, Saturn
and Mars are separated by less than the width of the full moon.
Saturn then moves on increasing
its separation from Mars
each day as a new addition to the morning sky makes its debut.
By mid-month, Jupiter is starting to rise
in the pre-dawn hour.
Making for a quartet of planets
strung out in a line across the morning sky.
Heading into the last week of April, Jupiter will be high
enough above the horizon in the
before sunrise to make it more easily observed.
The two brightest planets in the sky,
Venus and Jupiter, are headed
for their own ultra-close conjunction on April 30th,
similar to the meetup of Mars and Saturn earlier in the month.
In fact, they approach to about the same distance.
Of course, the planets
are actually far apart in space
and only appear to move closer or farther apart in the sky
as our view of them
across the solar system changes from month to month.
If you recall
the grand conjunction of Jupiter and Saturn at the end of 2020,
these conjunctions
are not quite as close as that,
but still really impressive
and they'll make for thrilling sights in the morning sky.
So definitely try to catch them if you can.
Whether you call it the Big Dipper
or Ursa Major or the Plough,
it's probably the
most familiar pattern of bright
stars in the northern sky.
The Big Dipper is a really useful reference
for finding your way around the sky,
but it also contains a hidden surprise.
One of its stars is really two...
Or, actually six...
Let's break that down.
What looks on first glance like a single
bright star here, midway along the Dipper's handle, is on
closer inspection, a double star Mizar and Alcor.
Next time you have a chance,
try to see
if you can perceive them as two stars with your own eyes.
Once you give it a try,
then grab binoculars if you have them,
which will easily show them as separate stars.
The two star systems are around
a light year apart
and are located 80 light years away
from our solar system, with Alcor taking
just shy of a million years to complete an orbit around Mizar.
Now, lots of stars are bound together
by gravity in small groups,
especially in pairs or binaries that orbit around each other.
But usually it takes a telescope
to be able to see them
as separate stars.
Mizar and Alcor are a rare example of a double star
that you can see as a pair
without the aid of a telescope.
But it gets more interesting.
Although they appear as a close
pair of two stars,
they are, in fact six.
Alcor is a binary pair of two stars, while Mizar
is actually four stars: two pairs of binaries.
So find the unusual "double" stars Mizar and Alcor
in the Big Dipper in April, where what at first appears as
one star is in reality a six-star system.
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.