Prepare your scantron: Use a pencil, not a pen! Fill in your name and fill the bubbles under your name. LAST NAME FIRST, First name second Put your 4-digit code instead of “IDENTIFICATION NUMBER”. --- (The last 4 digits of your OleMiss ID.) Question # 1: answer A Question # 2: answer C Question # 3: answer C Setup: Test 2 on Wednesday! Please take a moment to mute your cell phone!

Review questions coming …

This question counts double! sec 10 9 11 13 14 8 12 6 2 1 3 4 15 5 7 16 26 17 27 28 30 29 24 25 23 19 18 20 21 22 Question 4 The unit of seeing is … A magnitudes. B light years. C arc seconds. D parsecs. E nothing: seeing is a number without units. Next question coming …

This question counts double! sec 10 9 11 13 14 8 12 6 2 1 3 4 15 5 7 16 26 17 27 28 30 29 24 25 23 19 18 20 21 22 Question 5 The most important purpose of a telescope is … A bring far-away object closer. B to magnify the view by thousands of times. C to break up the light into colors. D to make dim object brighter. E to screen out damaging radiation from starlight. Next question coming …

This question counts double! sec 8 9 11 7 10 4 1 2 3 13 6 12 25 30 35 40 14 19 16 15 17 18 45 20 5 Question 6 What is the magnification of a 12-inch telescope, 120-inch focal length, when a 1-inch eyepiece is used? A 10 times. B 12 times. D 120 times. E 2.5 magnitudes. Next question coming …

This question counts double! sec 10 9 11 13 14 8 12 6 2 1 3 4 15 5 7 16 26 25 27 28 30 29 17 24 19 18 23 20 22 21 Question 7 How large is the smallest crater a good telescope can resolve on the Moon? A A foot. B A mile. C A hundred miles. D Two thousand miles. E No crater is visible on the moon with a telescope, only spacecraft images can show them.

The professional way of doing astronomy: picture taking and imaging Visual vs. CCD (1) Visual observation: always unreliable Recall the canals on Mars - G. Schiaparelli &P. Lowell

The professional way of doing astronomy: picture taking and imaging CCD (2) Photography: • reliable • can collect light for a long time (3) The modern way: CCD imaging • in CCD chip light moves electrons into pixel • computer counts electrons in each pixel and turns numbers into image on screen Similar to a digital camera but: • chip is cooled to reduce noise • computer controlled - image can be much improved with computerized processing techniques • many images can be added to improve quality The CCD revolution after 1995: one can take pictures even of galaxies with amateur equipment from light-polluted sites.

The Helix - a planetary nebula (amateur CCD image) Helix CCD

incredible resolution: Helix HST The Helix A Hubble telescope CCD image incredible resolution: 16,000 x 16,000

Questions coming …

sec 8 9 10 12 11 7 6 1 2 3 4 13 30 35 40 45 14 25 16 15 18 17 19 20 5 Question 8 Why do astronomers no longer look into their telescopes? A Because the observer’s body would obstruct the light in research-grade telescopes. B Because visual observations are unreliable. C Because there is dangerous radiation in a research observatory. D Because large telescopes collect so much light that their eyes would be damaged. E Because there is nothing left to discover in optical light; infrared and X-ray radiation must be observed to make new discoveries. Next question coming …

sec 8 9 10 12 11 7 6 1 2 3 4 13 30 35 40 45 14 25 16 15 18 17 19 20 5 Question 9 What is a CCD? A A new type of telescope that replaces reflectors. B A new type of optical device that replaces the lens or mirror of a telescope. C A new type of a telescope mount. D A new type of a detector that replaces photography. E A new type of an instrument that separates colors in starlight. Next question coming …

sec 8 9 10 12 11 7 6 1 2 3 4 13 30 35 40 45 14 25 16 15 18 17 19 20 5 Question 10 Which of the following is an advantage of photography over visual observations in astronomy? A Film has better resolution than the human eye. B Film can photograph X-rays, while the human eye cannot see them. C Film can collect light for a long time. D Film can be handled automatically in observatories in remote high mountains. E Seeing does not affect film photography.

Radio telescopes Advantage: can see radiation from charged particles flying in magnetic field between stars. Trouble: needs huge antennas for resolution and sensitivity Jodrell Bank Radio Observatory Interferometry: several antennas to work together improves resolution but does not help lack of ‘light’

X-ray astronomy - Chandra Launched: 1999 X-ray sources: when energetic charged particles hit magnetic fields • Supernova explosions • Supernova remnants • Black holes in nuclei of active galaxies • Glow of intergalactic gas

Infrared astronomy - Spitzer Launched: 2003 on solar orbit Infrared sources: not-so-hot objects Infrared light is not absorbed by interstellar dust as regular light is: can see through • Newly forming stars and their protoplanetary dust disks • The center of the Galaxy (behind dust) • Interstellar dust glows (10 - 100 K) • Small and not-so-hot stars (100 - 1000 K)

Centaurus A Centaurus A - an active galaxy at various wavelengths Optical and radio X-ray (Chandra) IR (Spitzer) Optical: starlight and dust obstruction Radio: charged particle jets in magnetic field X-ray: very energetic charged particle jets in magnetic field Infrared: cold (~100K) dust glows

Questions coming …

sec 10 9 11 12 15 14 13 8 7 1 2 3 5 4 6 16 26 17 27 28 30 29 24 25 23 19 18 20 21 22 Question 11 Name an object that we can see in infrared but not in regular light. A The Sun. B A supernova. C A hot star. D The center of the Galaxy. E An asteroid. Next question coming …

sec 10 9 11 12 15 14 13 8 7 1 2 3 5 4 6 16 26 17 27 28 30 29 24 25 23 19 18 20 21 22 Question 12 In what wavelength can we see newly born stars best? A Radio. B Infrared. C Optical. D X-ray. E Ultraviolet. Next question coming …

sec 10 9 11 12 15 14 13 8 7 1 2 3 5 4 6 16 26 17 27 28 30 29 24 25 23 19 18 20 21 22 Question 13 What objects can radio telescopes study most efficiently? A The Moon. B Interstellar matter. C Stars. D Comets. E The planets. Next question coming …

sec 10 9 11 13 14 8 12 7 2 1 3 4 6 5 15 17 26 25 27 28 30 29 16 24 19 18 23 20 22 21 Question 14 Why do we need to place X-ray telescopes on spaceships? A Because there is too much disturbing background X-ray radiation on Earth. B Because X-ray detectors must be cooled to the temperature of space. C Because X-rays get absorbed in the atmosphere. D Because the gravity of Earth repels X-rays from celestial objects. E Because we must get the X-ray detectors closer to the stars.