A nice fall weekend to watch the sky

WASHINGTON — Hey, DMV! For the next few mornings, the crescent moon will be sliding by Venus, Mars, Jupiter and Mercury in the East before sunrise.

This will be a pretty sight for those who are awake before sunrise. The moon will also show the ashen light of Earthshine, the reflection of sunlight off our planet’s oceans and clouds back into space.

This is a nice morning sequence and a warm up for the grouping of Mars, Jupiter and Venus later this month. I’ll let you know more about it in a future column.

When the skies finally cleared after our nor’easter, I took my first autumn picture of M-31, the Andromeda Galaxy. M-31 is the closest large galaxy to our own Milky Way Galaxy and contains about 1 trillion stars — our Galaxy only has several hundred billion stars.

It stretches out over 260,000 light years, as opposed to the Milky Way Galaxy’s 100,000 to 150,000 ligthht years. A light year is how far light, traveling at 186,000 miles per second, travels in one year. It is about 6 trillion miles.

The photo was taken with a 300mm f/4 telephoto lens, which tells you something about the size and relative closeness of M-31. You can see spiral arms, dust lanes, star clouds and M-110 to the immediate left and M-32 to the immediate right. M-32 and M-110 are two large dwarf galaxies of M-31.

The Andromeda Galaxy is the farthest object you can see with just your eye. It is 2.5 million light years away, which means the light I captured in this picture left M-31 about 2.5 million years ago! This is about the time in Earth’s history when our ancestors started walking upright.

If you look at this article and its star chart, you can see where Andromeda and M-31 are located. Look just off of the upper left corner of the Great Square of Pegasus. Pegasus is visible in the East as it gets dark and rises higher in the sky as the evening progresses. If you have binoculars you can see M-31 a lot better, especially if it is higher in the sky.

M-31 and our own Milky Way Galaxy are on a collision course, and will merge in about 4 billion years. The two galaxies are moving towards one another at about 250,000 miles per hour. The two smaller galaxies will turn into a giant new elliptical galaxy called Milkomeda.

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