Saturday: Has there ever been life on Mars? Astronomers don’t
know. But the Mars Curiosity Rover has been digging up some strong evidence
that Mars was hospitable to life in the past. At the end of 2012, the first
drilling assignment for Curiosity found clay-like minerals that form in the
presence of water. This past December, scientists announced the strongest
evidence yet for an ancient fresh-water lake in Gale Crater. Planetary
geologist John Grotzinger said that Earth microbes could have thrived in this
lake if they were placed there. For more information, go to http://goo.gl/7E6MD8. Mars is about one fist
held upright and at arm’s length above the east-southeast horizon at 11 p.m. The
bright star Spica is just to the right of Mars.
Sunday: While we may refer to the moon tonight by the boring
title, “a full moon in March”, Native Americans in the eastern United States
called this moon the Full Worm Moon. By March, the temperature has increased
enough so the ground starts to thaw and earthworms make their first appearance.
Earthworms attract birds. Northern tribes thought of the bird connection when
they referred to the March full moon as the Full Crow Moon. Tribes in parts of
the country with maple trees call this full moon the Full Sap Moon. For more
full moon names, go to http://www.farmersalmanac.com/full-moon-names.
Monday: Ask someone which day in March has the same duration
day and night. Go ahead, ask someone. Why are you still reading this? I can
wait. If that person said the first day of spring, they are wrong. Today, three
days before the first day of spring, is the date in which day and night are
closest in duration. There are two main reasons for this. First, the atmosphere
acts like a lens, bending light from the Sun above the horizon when the Sun is
actually below the horizon. This makes the Sun appear to rise before it
actually rises and appear to set after is actually sets. Second, spring starts
when the center of the Sun passes through the point called the vernal equinox.
But, the Sun is not a point. The upper edge of the Sun rises about a minute
before the center of the Sun and the lower edge sets a minute after the center
of the Sun. Thus, even if we didn’t have an atmosphere that bends the sunlight,
daytime on the first day of spring would still be longer than 12 hours.
Tuesday: Venus is one fist above the southeast horizon at
6:30 a.m.
Wednesday: Jupiter is six and a half fists above due south
at 8 p.m.
Thursday: Look up in the sky. It’s a plane. It’s a bird. No,
it’s the vernal equinox. The vernal equinox!? Spring starts at 9:57 a.m.
Pacific Daylight Time. The first day of spring is often called the vernal
equinox. This label for the day is misleading. The vernal equinox is actually
the point in the sky where the Sun’s apparent path with respect to the
background stars (called the ecliptic) crosses the line that divides the stars
into north and south (called the celestial equator). This point is in the
constellation Pisces the fishes. At the vernal equinox, the Sun is moving from
the southern region of background stars to the northern region. Since the Sun
crosses the vernal equinox at night, tomorrow will actually be the first full
day of spring.
Because the Earth slowly wobbles like a spinning top, the
vernal equinox is slowly moving into the constellation Aquarius. By the year
2597, the vernal equinox will reach the constellation Aquarius and the “Age of
Aquarius” will begin. Until then, we’ll be in “the age of Pisces”.
Friday: The moon is near Saturn late last night into early
morning. By the time both have risen at 1 a.m., Saturn is less than half a fist
above the moon. By 6 a.m., they have moved to the southern sky and are a little
bit farther apart.
The positional information in this column about stars and
planets is typically accurate for the entire week. For up to date information
about the night sky, go to https://nightsky.jpl.nasa.gov/planner.cfm.
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