Astronomy is looking up

by admin on July 15th, 2018

filed under 南京夜网

Mercury is faint but above and close to Venus on its right, and you can see them all in a clear sky, even without binoculars before twilight ends. See top diagram.
Nanjing Night Net

Moon OriginWhere did the Moon come from? This is not a simple, plain question easy to answer.Mercury and Venus have no moons.We have one, which is large and close to Earth.Mars has a pair of tiny ones, which may be captured asteroids.Jupiter and the outer gas planets have many dozens of Moons of all sizes.

Even little minor planet Pluto has several.But the question of our own Moon’s origin is a work in progress.

Its dust and rocks match Earth materials and their ages are close to the age of our planet.Astronomy is looking and thinking about what is observed(This sort of makes us all astronomers, really). The evidence suggests that not too long after its formation the Earth collided with a body, perhaps the size of Mars, sending earth-material into orbit which gradually merged to form our spherical Moon.

The Moon in its earliest times would have been smaller, faster and closer to Earth than now, but accumulating more material and later getting farther away and slower.It would take very many hundreds of millions of years.Then its speed of rotation would slowly reduce, eventually ceasing until the present stage where the same face of the Moon points towards us all the time.

This is ‘captured rotation’,a well attested result of orbital processes through time. You can check this outcome for yourself – watch a near full moon (e.g. August 17 to 19), if the sky is clear enough, at intervals through a night from evening in the east to dawn in the west.The Moon rotates at just the right rate to always point the same face to us.Think about it!

JupiterThe big planet is perfectly situated in the early evening sky for our viewing now and during August.

Look up at dusk, even before dark, high to the northwest.

Remember that the Juno spacecraft has been successfully in orbit around Jupiter since July 4, orbiting every 14 days and gathering information about the planet itself and its crucial role in the formation of our Solar System. Jupiter and Venus are of similar brightness.Mercury is faint but above and close to Venus on its right, and you can see them all in a clear sky, even without binoculars before twilight ends.SeeDiagram 1.

Remember,when looking west we on the spherical Earth are revolving backwards fast and planets near the horizon disappear downwards quickly.Venus and Mercury have risen up from behind the Sun, are coming towards us, and by the end of August will be above our line of sight to Jupiter. SeeDiagrams 2, 3.It will be a great opportunity to see their conjunction and spectacular combined brightness, at and near the dates shown.

PerspectiveThe Moon is between 360 and 400 thousand kilometres away from us. The Sun, Mercury and Venus are between 150 and 200 million kilometres away.But Jupiter is 800 million kilometres away and signals from Juno take nearly an hour to reach Earth.

MeteorsThe Perseid MeteorShower occurs for a month from mid-July each year.Look north to northeast ward in a dark sky during late night and early morning hours.The hourly rate can be from a few to many dozens per hour.

Stargazing- with David Reneke fromAustralasian Science magazineTwo powerful solar outbursts just last week in rapid succession caused blackouts for shortwave radio users around the world.

Most developed countries like Australia are particularly vulnerable because the power infrastructure is highly interconnected, so failures could easily cascade like chains of dominoes. Imagine large cities without power for a week, a month, or a year. The losses could be $1 to $2 trillion, and the effects could be felt for years.

So, the next time you get burnt red from being outside too long spare a thought for how powerful thatball of energy is that dominates the daytime sky.

“The Sun warms our planet every day, provides the light by which we see and is necessary for life onEarth,” Dave said.

“It produces poem worthy sunsets and releases as much energy as 1 trillion megaton bombs every second! Wow, that’s raw untapped power!”

This story Administrator ready to work first appeared on Nanjing Night Net.

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