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[Energetic music]

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[Preston Dyches]
What's Up for June?

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Planets buzz the Beehive,

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your bright evening stars,

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and how the Summer Solstice

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revealed the size
of planet Earth.

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On June 1st and 2nd,
Mars will be in the Beehive.

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The Red Planet passes
through the Beehive Cluster,

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also known as Praesepe or M44.

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It's a well-known open
cluster of stars located

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about 600 light years away

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in the constellation Cancer,
the crab.

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The pairing will make for great
viewing through binoculars

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or a small telescope,
with a sparkle of faint stars

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surrounding the rust-
colored disk of Mars.

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You can watch Mars and Venus
draw closer together

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throughout the month in the
western sky following sunset.

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Nearby is brilliant,
blue-white star

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Regulus, the heart of Leo,
the lion.

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And on the 20th

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through the 22nd,
the crescent moon passes through

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making an especially lovely
grouping at dusk on June 21st.

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Turning to the morning sky,
Saturn and Jupiter rise before

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dawn with the ringed planet
rising around midnight

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and leading brilliant Jupiter
into the new day.

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Early risers will find them

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on the eastern side of the sky
before sun-up all month long,

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and you'll find Jupiter rising
with the crescent moon

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on June 14th.

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Facing southward early
on June evenings,

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you'll notice two particularly
bright stars high up in the sky.

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They are Spica and Arcturus.

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Blue-white Spica
is the brightest star

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in the constellation Virgo,
the maiden.

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It's located
about 250 light years away

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and is actually two stars
orbiting each other

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every four days at a distance

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far closer than Mercury
orbits our sun.

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Orange giant Arcturus
is the brightest star

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in the constellation
Bootes, the herdsman.

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It's the fourth
brightest star in the sky.

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It's much closer than Spica,

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at a distance of
about 37 light years.

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It's also quite an old star,
compared to our sun,

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at an age
of 7-8 billion years.

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Also, on June evenings,
you'll notice

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the stars of the
Summer Triangle,

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Vega, Deneb and Altair,

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rising in the couple
of hours after dark,

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and heralding the long, warm
nights of Northern summer.

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The Triangle rises earlier
each month as summer progresses.

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June 21st is the Summer Solstice
for the Northern Hemisphere,

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and winter solstice
in the Southern Hemisphere.

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For the north, it's
the longest day of the year

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as the Sun traces its highest,
longest path across the sky.

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more hours of sunlight,
in addition to the more direct

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angle of the Sun overhead,

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translate into warmer summertime
temperatures for our planet's

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summer hemisphere.

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The situation is reversed

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for those living south
of the equator,

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where it's the shortest
day of the year,

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during the cool
months of winter.

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The June Summer Solstice has

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another interesting
claim to fame.

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It helped the ancient Greeks
2200 years ago to understand

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the size of our planet
with remarkable accuracy.

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A scholar named Eratosthenes
noted the difference

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in the length of the
shadows cast by poles

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placed in the ground
in two cities

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800 kilometers apart at noon
on the day of the solstice.

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One cast no shadow at all,

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and the other cast
a significant shadow.

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By comparing the shadows

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with the separation
of the two cities,

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Eratosthenes deduced
that Earth was about 40,000

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kilometers in circumference,
which is the actual value.

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He was also the first
to calculate the tilt of Earth's

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axis, which, after all, is
what's responsible

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for the solstices
and for the seasons themselves.

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Here are the phases

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of the Moon for June.

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Stay up to date
with all of NASA's missions

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to explore the solar system
and beyond at NASA.gov.

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I'm Preston Dyches from NASA's
Jet Propulsion Laboratory,

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and that's
What's Up for this month.