See Mercury and Venus orbits during the day

Your hands and arms help you see the orbits of Mercury and Venus and the shape of solar system

Question: If you could see the orbit of Venus would it fill the whole sky?

The answer might surprise you!

You can use your hands and arms to see the size of the orbits of the solar system’s inner planets: Mercury and Venus.

Imagine (as pictured below) if the orbit of Mercury were visible as a red oval and the orbit of Venus were visible in green.

Use your hands and elbows to see Mercury and Venus orbits any time of day or night. The orbits of Mercury and Venus can be seen.
Two hand spans show Mercury’s orbit, elbows show Venus’s orbit.

Physical Astronomy – see Mercury and Venus orbits

Caution! Do not look directly at the Sun without proper solar safety glasses on.

Turn toward the Sun, hold your arms out straight, hands up in the air with fingers spread wide and thumbs touching. Your pinky fingers now span the width of the orbit of Mercury and your elbows span the width of the orbit of Venus.

Both of the entire orbits of Mercury and Venus orbits would be visible in the sky all at once – if they could be made visible during the day.

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Shapes with Shadows – astrosketching Moon features with Alex Massey

Shapes with Shadows – what they can tell us

This the first of two special guest posts by Australian astrosketch artist Alexander Massey 

Live View Sketch of Moon craters Azrachel, Alphonsus, and Ptolemaeus by Alex Massey

Ptolemaeus, Alphonsus, and Arzachel… the names of three massive, interlocking craters on the Moon. These three craters tell the story of the ancient Moon’s creation and evolution. It’s a story of violent bombardments and oceans of lava. We can use light and shadows to reveal the shapes and deep history of these features.

Most people think of astronomy a science of light. But, light creates shadows when it hits things. Those features that lie in the shadows, the dark parts and seemingly just-in-the-way-of-the-light parts, are just as important as those that shine brightly. These dark shadows form most of the mass of all galaxies, house stellar nurseries, reveal old lava rivers on the Moon, and create curious plays of light and dark. These can play tricks on our eyes and make patterns appear.

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Galaxy Rise

Physical Astronomy by Daniel Cummings

A still more glorious dawn awaits Not a sunrise, but a galaxy rise A morning filled with 400 billion suns The rising of the milky way.

The Sun rises. The Moon rises. Stars rise. The Galaxy rises – twice.

Each day the Earth rotates and sky objects (seem to) rise in the Eastern sky. The Sun, the Moon, the Stars, and the Galaxy rise at various times.

The Sun “rises” once-a-day at the start of the day.

The Moon “rises” once-a-day at different times of the day and night depending on the moon’s orbit around the Earth (its phase).

The Stars “rise” once-a-day – all night long, one after another and in groups.

The Milky Way Galaxy “rises” twice a day – once on its bright (center) side and then 12 hours later on its dim (outer arm) side.

We can orient our bodies to the rising of the Milky Way. And we can experience our daily movement as “plunging through” this flat disk of stars.

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Super Moon December 3rd, 2017

Super Moon

The closest approach that the moon will make on its monthly orbit around the Earth coupled with a Full Moon. The December 3rd Super Moon is here!

Here is an image showing how the arrangement of the Moon’s “Perigee” with the Full Moon results in the Super Moon.

Supermoon arrangement of moon's orbit around the Earth
Schematic showing how the “Super Moon” happens and the change in apparent size of the moon. The Moon appears about 14% larger during a Super Moon event.

The Full Moon + Orbit at Perigee = Super Moon.

Walk to Mintaka

Physical Astronomy by Daniel Cummings
Mistakable rises toward the zenith as you walk toward the equator
As you walk toward the equator, Mintaka appears to rise higher in the sky.

In this post we will learn how to use one bright star of Orion’s belt to visualize the Earth’s equator.

Mintaka is a Star in Orion’s Belt

When you look up at the winter sky in the northern hemisphere, Orion and his famous belt are impossible to miss. The belt is made up of three stars of equal brightness.

One of these stars is called Mintaka and it is a guidepost for finding the Earth’s equator in space. Click here to continue reading…

Tilt Head to Tilt Earth

Physical Astronomy by Daniel CummingsTilt your head to tilt the earth and experi nice the seasons

Seasons are caused by a tilted Earth

Use this technique to understand how seasons happen on the Earth. The Earth is tilted. When the northern part (your forehead and eyes) tilts away from the Sun the season is winter. When the northern part tilts toward the Sun the season is summer.

The Earth is tilted as it spins daily – it is not straight up and down like a top, but more like the Leaning Tower of Pisa (if the tower could spin!). As it goes through its yearly orbit, the Sun hits the northern and then the southern parts of the Earth.

Tilt your head to tilt the Earth

In this model, when the northern part (your forehead and eyes) tilts away from the Sun the season is winter. When the northern part tilts toward the Sun the season is summer.

Did you like this season model? Any questions? Type in the comments to send me a message.

The Moon is Upside Down

The Moon is Upside Down

The moon is upside down (as seen from the Southern Hemisphere)
The moon as seen from the Southern Hemisphere. source: Wikipedia.

When you are in the southern hemisphere, the moon looks upside down.

When I came back to the US from living in Australia for 4 years, I published a poster with a picture of the moon on in and I placed it “upside down” – someone pointed it out and I looked at the moon and said “the moon is upside down.” This was true – in the Northern Hemisphere – but to people living in the Southern Hemisphere the moon appears “upside down.”

I was shocked, but the claim was true – in the Northern Hemisphere! But to Australians and other people living in places in the Southern Hemisphere the moon appears “upside down.”

 

Arms around the ecliptic

Learn to see the ecliptic

Physical Astronomy by Daniel Cummings

Ecliptic Arms

The sun follows the same path through the sky every day.

Sun up. Noon. Sun down.

The sun starts the day in the east in the morning, rises high in the sky at noon, and settles down again in the west for a nap at night.

See the ecliptic

Here is an exercise to discover that path – the ecliptic.

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Train your Brain – See the shape of the solar system

Physical Astronomy by Daniel Cummings.

Train your Brain - See the solar system disk

See the solar system from Earth

Most people, when they look up at the night sky can easily see stars and identify some familiar groups of stars (asterisms and constellations). Some people can even find and name some planets – Venus, Jupiter, and Mars are all bright and easy to see.

But, there are many invisible wonders in the sky – and some of them can be seen without a telescope. In fact they are so big that a telescope is not the right tool to use; we have to use something even more powerful… imagination!

Using visualization and imagination, I am going to show you how to find and “see” a very large structure in our sky: the solar system disk itself.

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Night is…

“‘Night’ is not what time it is… it is where you are.” – Daniel Cummings