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Astronomy Fact of the Day

Fun astronomy facts to impress your friends with! 

Astronomy Fact of the Day for October 2017. 

Check back next month for more astronomy facts!

1st – Tonight the Moon will exhibit a waxing gibbous phase. You will be able to see about 82% of the lunar disk illuminated by sunlight.

2nd – Looking south at 8:30 pm you will find the bright star Fomalhaut. It is located in the constellation Pisces Austrinus. It is the 18th brightest star in the night sky.

3rd – NOAA or the National Oceanic and Atmospheric Administration was found on this date in 1970. Aside from monitoring weather and the environment on Earth they also monitor space weather.

4th – Tomorrow morning you can find Mars and Venus together low in the eastern sky. Your best chance to see the pair will be around 6am. Be careful this is only 1 hour before sunrise.

5th – Full moon occurs today at 12:40pm. October’s full moon is sometimes called the Full Hunter’s Moon.

6th – Public Telescope Viewing will be held at the James S. McDonnell Planetarium tonight with the St. Louis Astronomical Society. For more information visit

7th – Looking northeast tonight at 8:30pm, you will find the “W” shape of the constellation Cassiopeia.

8th – On this date in 1873 Danish astronomer Ejnar Hertzsprung was born. He helped create the Hertzsprung–Russell diagram which astronomers use to study star types and stellar evolution.

9th – The average distance between the Earth and Sun is roughly 93 million miles. This is an astronomical unit (AU). By comparison Mars’s average distance is 1.5 AU and Pluto’s is 39.5 AU.

10th – If you go outside tonight at 8:30pm you can find the planet Saturn about 10° about the south western horizon. Tonight Saturn will be roughly 967 million miles from Earth.

11th – Tomorrow at 12:47am a small 15-30 meter asteroid named 2012 TC4 will pass 31,000 miles from Earth. This asteroid poses no threat to Earth but if it were to impact Earth it would be similar to the Chelyabinsk meteor from 2013.

12th – Last quarter moon occurs today. During first and last quarter phases of the Moon, Earth experiences neap tides. This is when there is the least different between high and low tides.

13th – The constellation Pegasus is flying high overhead tonight at 10pm. To find him look near the zenith for a large square shape. This is often called the Square of Pegasus.

14th – Today in 1947, Chuck Yeager piloted the Bell X1 rocket plane in the first supersonic flight.

15th – Today in 1997 NASA launched the Cassini-Huygens mission. The Huygens probe landed on Saturn’s moon Titan and the Cassini probe studied Saturn until September 15, 2017.

16th – Of all the mass in our solar system roughly 99.86% of it is in the Sun. This would be the equivalent to roughly 332,946 Earths.

17th – Today in 1956, astronaut Mae Jemison was born. In 1992 she served as mission specialist on board the space shuttle Endeavour. During this flight she became the first African American woman in space.

18th – The Orionid meteor shower peaks on Oct. 22 but is currently active. This meteor shower is caused as Earth passes through debris from Comet Halley. The best chance to see meteors will be after midnight looking east.

19th – New moon occurs today. When the Moon is at new or full phase the Earth experiences spring tides. This is when there is the greatest difference between high and low tides.

20th – Today in 1963, Canadian astronaut Julie Payette was born. Julie was a crewmember on space shuttle Discovery in 1999. She was the first Canadian to participate in construction of the International Space Station.

21st – Mars has started to climb out of the Sun’s glare. It is now on its way to its next opposition on July 27, 2018 when it will be 35.7 million miles from Earth. Currently Mars can be seen rising around 4:54am.

22nd – The first recorded solar eclipse occurred on this date in 2137 BCE. It was found in ancient Chinese astronomical records.

23rd – As stars go the Sun is an average size star with a diameter of 864,337.2 miles. At this size it would take roughly 109 Earths to go from one side of the Sun to the other.

24th – On this day in 1977 NASA launched the satellite NIMBUS 7. Observations from this mission between 1978 and 1994 helped confirm the depletion of the Ozone layer in our atmosphere.

25th – Looking to the east around midnight you will see the constellation Orion the Hunter. The red star Betelgeuse located in his shoulder is the 10th brightest star in the night sky!

26th – The red supergiant star Betelgeuse is one of the largest and most luminous stars visible to the unaided eye. If you put it in our solar system it would extend beyond the main asteroid belt.

27th – First quarter moon occurs today. Look for the Moon in the western skies after sunset.

28th – If you look east tonight at 9:30pm you will see a bright V-shape of stars. This is called the Hyades. It is an open star cluster that is 150 ly from Earth making it one of the closest.

29th – The Sun is the largest object in our solar system. If the Sun was hallow you could fit 1.3 million Earths inside the Sun.

30th –Tonight the Moon will be exhibiting a waxing gibbous phase with about 76% of the lunar disk illuminated. You can find it in the early evening in the southeastern skies.

31st – Tonight if you look east at 10:30pm the brightest star you see is called Capella. This is the 6th brightest star in the sky, it is not 1 but 4 stars and it can be found in the constellation Auriga.


First 7 days of November

1st – Tonight the Moon will be exhibiting a waxing gibbous phase. The dark patches you see on the Moon are called Maria. These were produced when lava once poured onto the Moon’s surface.

2nd – In the morning of Nov. 5 the Southern Taurid meteor shower will peak around 6am. For the best chance to see meteors go outside at 10pm and look east. Your chances will improve once Taurus climbs higher in the sky.

3rd – Public Telescope Viewing will be held at the James S. McDonnell Planetarium tonight with the St. Louis Astronomical Society. For more information visit

4th –Daylight saving time ends tomorrow at 2am. We will be returning to Central Standard Time (CST) so remember to set your clocks back one hour.

5th – At 7:04pm the bright star Aldebaran will be occulted by the Moon. During this you will see the bright star disappear behind the Moon. Unfortunately it occurs shortly after moonrise. Aldebaran will reappear at 7:51pm.

6th – The Moon is at perigee tonight. This is when the Moon is closest to Earth. During this perigee the Moon will be 361,438 km from Earth.

7th – Tonight if you look east at 10pm you will see the three stars of Orion’s Belt. What appears to be three stars is really about 80. Orion’s Belt is a star cluster called Collinder 70.

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