Showing posts with label astronomer. Show all posts
Showing posts with label astronomer. Show all posts

May 10 - Happy Birthday, Cecilia Payne-Gaposchkin

   Posted on May 10, 2022

This is an update of my post published on May 10, 2011:




Don't you love it when someone reveals a whole new understanding of the universe?

And when that “someone” is a woman, you'd think she was unusual enough that we would have all heard of her! But I don't ever recall seeing this English-American astronomer's name before I first wrote about her in 2011!


Born on this day in 1900, Cecilia Payne studied botany, physics, and chemistry at Cambridge, in England. She completed her studies but didn't get a degree. You've probably already figured out it was because she was a woman—yep, Cambridge did not award degrees to women, back then!

While at Cambridge, Payne became fascinated by astronomy, and she went to the U.S. to study astronomy at Radcliffe (now part of Harvard). She was the first person to earn a PhD in astronomy at the college—and her paper (doctoral dissertation) was considered brilliant by at least some readers.

What Payne did was relate the type (spectral class) of stars to their actual temperatures, and she showed that the variation of the placement of the lines in a star's spectrum was caused by different temperatures, not just different amounts of the various elements.


At the time, people were sure that the Sun and other stars was made up of the same stuff as the Earth. That was what is called “the accepted wisdom” of the time. However, Payne's analysis indicated that the Sun had a lot more helium and a MILLION times more hydrogen than the Earth!

Unfortunately, Payne was just a student, and a more well-established astronomer named Henry Norris Russell persuaded her not to put forth that conclusion. Later, other evidence emerged showing that Payne, not “accepted wisdom,” was right.

And here's where science shines: Russell looked at the evidence, accepted the evidence, and changed his mind.

Here's where science doesn't always shine: once Russell, the older and more famous astronomer, changed his mind and accepted Payne's conclusion, many other scientists gave HIM, not her, the credit!

Aack!

Anyway, I have heard of Russell, because of the famous Hertzsprung-Russell diagram showing the different types of stars. 





 
(By the way, Payne later married and became Cecilia Payne-Gaposchkin).


For more...

Read about the life and death of an average star. 

Learn about different types of stars here. 

Here are printables you can use to learn more about stars.


 



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February 4 - Happy Birthday, Clyde Tombaugh

  Posted on February 4, 2022


This is an update of my post published on February 4, 2011:




How would you like to be the first person to discover a dwarf planet? How'd you like to be the only person in the twentieth century to discover a planet? How about being the one who discovers the first Kuiper Belt Object?

Clyde Tombaugh, who was born on this day in 1906, got to be all three...all because he discovered Pluto!

During Tombaugh's lifetime, Pluto was considered the ninth planet.

Because of recent discoveries of many other objects from as far away as the orbit of Neptune out to 55 A.U. from the sun, astronomers decided that Pluto was just a large-sized example of a rocky / icy body in an entire wide belt of rocky / icy bodies. This belt is called the Kuiper Belt, and so Pluto is now considered a Kuiper Belt Object (KBO).


When I say that there are “many” KBOs...I'm talking thousands and thousands! There are more than 70,000 KBOs that are larger than 100 km (62 miles) in diameter. Several of these KBOs are large enough to be considered dwarf planets: Eris (which is larger than Pluto), Pluto, Haumea, and Makemake. Some of the moons of planets (such as Neptune's Triton and Saturn's Phoebe) are considered to have once been KBOs, and the dwarf planet Pluto has a relatively large moon, Charon, plus two smaller moons, Nix and Hydra, that are of course also KBOs.

The name for a dwarf planet that is in the Kuiper Belt is plutoid. So we could also say that Tombaugh discovered the first plutoid!






So Pluto was a planet and is now a plutoid, a Kuiper Belt Object, and a dwarf planet—and Clyde Tombaugh's guarantee of inclusion in the history books.


By the way...

  • Tombaugh was just 24 years old when he discovered Pluto.
  • Tombaugh wanted to go to college, but hailstones ruined his family's crops and spoiled his hopes for being able to afford it. He didn't give up! He built several telescopes, grinding the lenses and mirrors himself, and he sent drawings of Jupiter, Mars, and the telescopes to the Lowell Observatory in Arizona. This bold move resulted in Tombaugh being offered a job in 1929. It was on the job as an astronomer that Tombaugh made his big discovery.
After discovering Pluto, Tombaugh was able to finally go to college (apparently while still keeping his job). He ended up getting both a bachelor's and a master's degree in astronomy. 
  • Tombaugh discovered nearly 800 asteroids, a comet, hundreds of variable stars, star clusters, galaxy clusters, and a galaxy supercluster.
  • Tombaugh helped to choose the name Pluto, but he didn't think of the name himself. Instead, a little girl, age 11, who lived in far-away England, made the suggestion... Venetia Katharine Douglas Burney was excited about the discovery of a ninth planet and suggested the name Pluto, who was the Roman god of the underworld. It seems that Burney made that particular suggestion partly because the other planets are named for Roman gods and partly because Pluto-the-god had the power to turn himself invisible—and Pluto-the-planet had been so hard to discover, it was as if it had the power of invisibility.

One reason Tombaugh liked and chose the name Pluto is because the first two letters, P and L, are the initials of the astronomer who predicted that there would be a planet beyond the orbit of Neptune. Percival Lowell was a wealthy man who founded the observatory in which Tombaugh worked and who urged the search for “Planet X,” which, Lowell claimed, slightly displaced both Uranus and Neptune from their orbits. Unfortunately, Lowell died at age 61, fourteen years before Planet X was discovered and named Pluto.

  • Did you know that Russia has more land area than Pluto? Wow!


 

 


Poor Pluto?

A lot of people seem to be upset that Pluto has been “demoted” from being a planet to being a mere dwarf planet. They seem to feel hurt on behalf of poor Pluto, as if they were worrying about the feelings of Mickey Mouse's beloved dog Pluto. (By the way, the Disney pup Pluto was named after the planet/dwarf planet—the whole world was excited by its discovery!)

If you worry about poor Pluto, read this clear and accurate explanation why the new label for Pluto as a dwarf planet is better science.


All of these dwarf planets are also KBOs, except Ceres. 
Ceres is classified as a dwarf planet, but it circles the Sun
between Jupiter's orbit and Mars's orbit - in what is
considered the asteroid belt.

Because Ceres is a one-of-a-kind dwarf planet (by location)
AND a one-of-a-kind asteroid (by size), it isn't a plutoid,
 and we don't need another classification such as a Ceroid.

 
Remember, as Fraser Cain clearly points out in the link above, one of the recently discovered Kuiper Belt Objects is larger than Pluto. If Pluto were to still be considered a planet, Eris would have to be, too. No matter what, we can't hold onto a solar system with nine planets—at this point, we can either have 8 or we can have 10, 12, or more—depending on where you draw the cut-off line of size between planets and dwarf planets. Astronomers have decided on a good, solid definition for planet that dictates that the solar system has 8 planets.

Another reason we don't have to worry about poor Pluto's feelings (aside from the fact that it doesn't have any feelings) is that - as we pointed out above - an entire class of solar system objects is named plutoid for Pluto. Like, there are no such things as Earthoids or Saturnoids. So...that's pretty rad!

  • NASA has a page on Pluto and the Kuiper Belt and several other dwarf planets. (Click this link and then tap Planets on the menu bar. The drop down menu includes Pluto and four other dwarf planets). 



 


(First Friday of February)
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November 24 - First Observation of a Transit of Venus

  Posted on November 24, 2021


This is an update of my post published on November 24, 2010:



Every once in a while, one of the planets gets between us and the Sun. These planets are too far away to cast a shadow on our planet or to block much of the sunlight—in other words, they don't eclipse the Sun like the Moon occasionally does. Instead, from our point of view, they appear as tiny black dots that travel across the disc of the Sun. This is called a transit.

Only two planets can be seen in transit across the Sun from the Earth. Do you know which ones they are?

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ANSWER: Mercury and Venus are both closer to the Sun than we are here on Earth, so they are the only planets that can get between us and the Sun.



Anyway, Jeremiah Horrocks was an English astronomer. He was the only person known to have predicted the transit of Venus on this date in 1639, and he is one of only two to have observed and recorded it. (His friend William Crabtree was the other.)

You may be wondering how he—or anybody—could watch a transit across the blindingly bright Sun. Well, he focused the image of the Sun through a simple telescope onto a piece of cardboard. He then watched the not-so-bright image on the cardboard. People still make this simple kind of helioscope these days, although astronomers have of course figured out more sophisticated systems with which they study the Sun.

NOTE: Never look at the image of the Sun EVEN with a helioscope without adult supervision.


A Rare Treat!

Transits of Venus are very rare. They happen in pairs that are eight years apart—and these pairs are separated by around 100 years! The last two transits of Venus occurred in 2004 and 2012. For many of us, that will likely be the last of our lifetimes! The next transit will be in December, 2117.

Transits of Mercury are much more frequent. The last one was in 2019, and the next one will be in 2032.


Notice how much larger Venus's dark disk looks
against the brightness of the Sun (above),
compared to Mercury's teeny spot (below),












Tie One On Day in the U.S.

(Day before Thanksgiving in the U.S.)






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