Kloppenborg et al. 2010, Nature, 464, 870

Zhao et al. 2008, ApJ, 684, 95

Roettenbacher et al. 2016, Nature, 533, 217

Spotted magnetic stars

Interacting binaries

Schaefer et al. 2014, Nature, 515, 234

Expansion curve of Nova Del 2013.

Regulus -- Che et al. 2011, ApJ, 732, 68

Rasalhague -- Zhao et al. 2009, ApJ, 701, 209

Altair -- Monnier et al. 2007, Science, 317, 324

Alderamin -- Zhao et al. 2009, ApJ, 701, 209

Beta Cas -- Che et al. 2011, ApJ, 732, 68

What's an exo-planet?

• Planets must orbit the Sun
• Planets must be large enough that their gravity forces their shape to be spherical
• Planets must clear their orbits of other material, so they are the largest body near their orbit

What's a planet?

• All the above except: Planets must orbit the Sun

https://exoplanets.nasa.gov/alien-worlds/ways-to-find-a-planet/

https://exoplanets.nasa.gov/

• Hot Jupiters
• lava planets
• rogue planets
• tidally locked/eyeballs
• multiple worlds

https://www.nasa.gov/feature/jpl/20-intriguing-exoplanets

• lethal rain
• devoured planets
• evaporating planets
• eccentric orbits
• ocean planets
• zombie planets
• circumbinary planets

Unlike most illustrations of this kind, in this graphic, the Earth and the Moon are to scale. The Sun is off-screen to the left, about 400 times farther than the Earth-Moon distance and roughly twice as big as the Moon's orbit.

The only safe way to look directly at the uneclipsed or partially eclipsed sun is through special-purpose solar filters, such as “eclipse glasses” or hand-held solar viewers*. Homemade filters or ordinary sunglasses are not safe for looking at the sun

 *verified to be compliant with the ISO 12312-2 international safety standard

• Inspect your solar filter before use; if scratched or damaged, discard it.
• Always supervise children using solar filters.
• Cover your eyes with your eclipse glasses before at the Sun. Do not remove it while looking at the sun.
• Do not look at the uneclipsed or partially eclipsed sun through an unfiltered camera, telescope, binoculars, or other optical device.
• Do not look at the sun through a camera, a telescope, binoculars, or any other optical device while using your eclipse glasses or hand-held solar viewer — the concentrated solar rays will damage the filter and enter your eye(s), causing serious injury.
• Seek expert advice from an astronomer before using a solar filter with a camera, a telescope, binoculars, or any other optical device. Note that solar filters must be attached to the front of any telescope, binoculars, camera lens, or other optics.
• If you are within the path of totality , remove your solar filter only when the moon completely covers the sun’s bright face and it suddenly gets quite dark. Experience totality, then, as soon as the bright sun begins to reappear, replace your solar viewer to look at the remaining partial phases.
• Outside the path of totality, you must always use a safe solar filter to view the sun directly.
• If you normally wear eyeglasses, keep them on. Put your eclipse glasses on over them, or hold your handheld viewer in front of them.

Bailey's Beads

"Diamond Ring"

Solar Prominence

ruby-red light of hydrogen gas heated to more than 20,000° Celsius (36,000° Fahrenheit)

Butler, 1918

Approach of the Moon's Shadow

https://www.americanscientist.org/article/the-art-and-science-of-solar-eclipses

Georg von Peurbach, Theoricæ nouæ planetarum, 1423-1461

https://www.theatlantic.com/science/archive/2016/09/an-artists-view-of-an-eclipse/498548/

Astronomy Explained, James Ferguson, 1757.

Etienne Trouvelot, Lithograph in colour, Total eclipse of sun; observed 29 July 1878

Roy Lichtenstein, Eclipse of the Sun I (left), II (right), Oil and Magna on Canvas, 1975

Zakariyya ibn Muhammad al-Qazwini, pages from “Aja’ib Al Makhluqat wa Ghara’eb Al Mawjodat” (The Wonders of Creation), 1203-1283

https://artmejo.com/eclipses-throughout-art-history/

Image from On the Moon written by Konstantin Tsilkovsky in 1887

https://royalsocietypublishing.org/doi/10.1098/rsta.2015.0211

Phobos eclipse on Mars from Perserverence, 2019

This graph shows the average October cloud cover (2000-2018) from satellite measurements at 10:30 am local time along the centerline of the October 14, 2023, annular eclipse track. Units are fractional sky cover, which can be interpreted as percent cloud cover. Courtesy Jay Anderson, Eclipsophile.com.

https://exoplanets.nasa.gov/alien-worlds/ways-to-find-a-planet/

https://exoplanets.nasa.gov/alien-worlds/ways-to-find-a-planet/

https://exoplanets.nasa.gov/alien-worlds/ways-to-find-a-planet/

There's about 5077 stars visible by naked eye. Which works out to 404 stars per sterradian.

So if you hold an iphone out at arm's distance, there’re about 50 visible stars in that amount of sky

There’s estimated to be 200 billion galaxies. Which works out to about 15.9 billion per sterradian.

An iphone 12 screen pixel is ~0.3mm.

There’re about 1,400 galaxies in the area of that single pixel.

An estimate of the number of stars per galaxy is 100 billion. 

So that puts around 

140,000,000,000,000 stars in the area of that single pixel

https://xkcd.com/2596/

Oxygen

• get transmission spectrum of the atmosphere
• measure different radii at different wavelegnths to give clues to composition

Types of

exoplanets

https://exoplanets.nasa.gov/alien-worlds/exoplanet-travel-bureau/

https://exoplanets.nasa.gov/alien-worlds/galaxy-of-horrors/

https://exoplanetarchive.ipac.caltech.edu/

Giordano Bruno

(1548 – 1600)

Italian Friar

• proposed stars were distant suns surrounded by their own planets
• possibility that these planets might foster life of their own
• insisted that the universe is infinite and could have no center

1593 - was tried for heresy and later burned at the stake

Oct 1995