Play with this.

http://exoplanets.newscientistapps.com/


Also, make sure that your sundial (due by the end of next week) will have a correction table.

Laika

http://www.fromquarkstoquasars.com/laika-the-first-earthling-in-space/

Eclipses

http://www.cnn.com/video/data/2.0/video/world/2012/11/13/vonat-australian-eclipse-timelapse.slooh-com.html

http://www.youtube.com/watch?v=3_qo2CdcyC0

http://www.youtube.com/watch?v=WYTdwwcLCT8

Total Lunar Eclipse
http://www.youtube.com/watch?v=mhZWIgUUPZ8

Phases of the Moon

http://astro.unl.edu/naap/lps/animations/lps.html

http://www.astro.wisc.edu/~dolan/java/MoonPhase.html

http://www.moonconnection.com/moon_phases.phtml

Notes on Time and Space

A discussion on Time:

The second is the fundamental unit of time. It was originally defined as: - the amount of time required for a 1-m pendulum to swing from one side of arc to the other

Now, it is defined as: 9 192 631 770 cycles of radiation corresponding to the transition between two hyperfine levels in the ground state of Cesium-133

Worth noting: There are approx 365 1/4 mean solar days in one solar year (watch time). The mean solar day is the average length of a solar day, 24 hours.

Solar year - the time between 2 vernal equinoxes. This is actually the tropical year, which is growing shorter by 0.5 sec/century. 1900 is the standard tropical year.

Sidereal time - time by the stars

Sidereal year - the amount of time for the Sun to return to a given position among stars

Calendars:

Julian - 365 days with an extra day every 4 years (leap year).
This was still a bit imprecise - consider that in 1988, the year was 365 d, 5 h, 48 min, 43.5 s. By 1582, the Julian calendar was out of phase with Easter by nearly 10 days. So, Pope Gregory XIII adopted a new calendar; 10 days were dropped from that year.

Gregorian calendar -
Years evenly divible by 4 are leap years. Every 4th century year is a leap year (2000, 2400; NOT 1600, 1700, 1800, 1900, 2100)

Daylight savings time
http://en.wikipedia.org/wiki/Daylight_saving_time
http://www.timeanddate.com/time/dst/

Changed a few years back. Now: DST Starts at 2 AM, second Sunday in March - set clocks AHEAD 1 hour
DST Ends at 2 AM, second Sunday in November - set clocks back

We are EST, Eastern Standard Time. During DST, we become EDT (Eastern daylight time).

Greenwich Mean Time (GMT) - 5 hours ahead of EST. Roughly the same as Universal Time (UT).

Universal time (UT)
Basically the mean solar time as measured on the Greenwich meridian, thus, 5 hours ahead of us. Formally, UT is defined by a mathematical formula as a function of sidereal time and is thus determined by observations of stars.

Sidereal time
In 365 1/4 solar days, Earth makes 366 1/4 rotations on its own axis. So, there are 366 1/4 sidereal days in a solar year. Each sidereal day is shorter by about 4 minutes than a solar day. UT and GST agree at one instant every year (at the autumnal equinox, around Sep 22). Thereafter, the difference between them grows, in the sense that ST runs faster than UT until exactly half a year later, when it is 12 hours. Another half-year later, the times again agree.

Local Sidereal Time - the hour angle of the first point of Aries

Greenwich Sidereal Time
local sidereal time on the Greenwich meridian

Julian Date (JD)
Jan 1, 4713 BC is the fundamental epoch from which this is decided. The Julian date is the number of days since this day.
There is no year 0 in astronomy. The year before 1 AD is defined as year 0. So, 10 BC is the year -9 in astronomy. That trick again: to go from BC year to astro year, subtract one and change sign.

>


Coordinate systems:

On Earth:

Longitude
half-circle lines from North to South pole
Zero longitude runs through the site of the Royal Greenwich Observatory in England - the Prime Meridian (0 degrees long.)
Number of degrees east or west of the PM

Latitude
Full circle lines parallel to the equator (0 degrees latitude)
+ or - 90 degrees corresponds to the poles

International Date Line (IDL)
Near or along 180 degrees longitude line, through the Pacific Ocean
As we travel eastward around the globe, the hours get later roughly each 15 degrees (a time zone). When we cross the IDL, we go BACK one day. This keeps only 24 hours on the Earth at a time.

In the Sky:

Celestial Equator - imaginary line above the Earth's equator

Right Ascension (RA)
Celestial analog of longitude (both measure east-west)
Measured in hours (each hour of RA equals 15 degrees) along the celestial equator

Declination (dec)
Celestial analog of latitude (both measure north-south)
Measured perpendicularly above (+) or below (-) the celestial equator

RA and dec form a coordinate system fixed to the stars. To observers on Earth, the stars appear to revolve every 23 h 56 min. So, the coordinate system appears to revolve at the same rate. Of course, it is the Earth which is really moving (most noticeably).

Ecliptic
Although the stars are fixed in their positions in the sky, the Sun's position varies through the whole range of RA throughout the year. This path (the "apparent" path of the Sun) is called the ecliptic and is inclined 23.5 degrees with respect to the celestial equator (CE), since the Earth's axis is tipped by that amount. (The "ecliptic plane" is the plane that the Earth and Sun make.)

The ecliptic and CE cross at two points:

Vernal equinox
March 21 (approx)
the first day of Northern Hemisphere spring
the zero-point of RA
Sun's declination is 0 degrees
Nearly equal amounts of day and night

Autumnal equinox
Sep 23 (approx)
the first day of autumn
Sun's declination at 0 degrees
Nearly equal amounts of day and night

Two other noteworthy days:
Winter solstice
Dec 22 (approx)
Shortest day of the year in Northern hemisphere
9.5 h of daylight (in the DC area)
As you travel farther north, the days are even shorter
- in Anchorage, Alaska, the day will be 5 h long
- in Barrow, Alaska, the sun will not "come out" at all; noontime is like deep twilight
the North pole is angled most steeply away from the Sun

Summer solstice
June 21 (approx)
longest day of the year in the Northern hemisphere
amount of tipping toward Sun is greatest for N. hemisphere
Sun highest in sky (dec is 23.5 degrees)

Length of daylight depends on latitude, calendar date, but not longitude
Each point on the globe receives an average of 12 hours of light each day. So, students in Barrow, Alaska have several days of endless sunshine as well.

Since the Moon goes around the Earth, its RA changes through the entire range of values each month. Since its orbit is inclined to the CE, its dec also changes.

Cool.

Harvest Moon - worth a read

http://earthsky.org/space/harvest-moon-2

http://curious.astro.cornell.edu/question.php?number=280

Harvest Moon Occurs Today:

A lot of people assume that a Harvest Moon is simply a name that we use to refer to the Moon when it looks orange. However, not all orange Moons are Harvest Moons.

In truth, "Harvest Moon" is just a term that we use to describe the full Moon at a particular time in the year – it is the name for the full Moon nearest the autumnal equinox. That makes the Harvest Moon September 18-19 in the Northern Hemisphere; in Asia, this full moon falls on the night of September 19-20. ...

Ultimately, the orange coloring that we frequently see stems from the fact that – when you look toward the horizon – you are looking through a greater thickness of Earth’s atmosphere than when you gaze up and overhead. The atmosphere scatters blue light – that’s why the sky looks blue. The greater thickness of atmosphere in the direction of a horizon scatters blue light most effectively, but it lets red light pass through to your eyes. So a moon near the horizon takes on a yellow or orange or reddish hue.

Some numbers to consider

Radius of Earth = 6.4 x 10^6 m

Radius of Moon = 1.74 x 10^6 m

Radius of Sun = 6.96 x 10^8 m

Distance from Earth to Sun (on average; one "Astronomical Unit" or AU) = 1.5 x 10^11 m

Distance from Earth to Moon = 3.84 x 10^8 m

Mass of Sun (one "solar mass") = 2 x 10^30 kg

Mass of Earth = 6 x 10^24 kg

Speed of light (in a vacuum) = c = 3 x 10^8 m/s

Find the following:

1.  Distance between Earth and Moon, in Moon diameters.  Visualize this with a globe and ball to represent the Moon.

2.  Distance from Earth to Sun, in Earth diameters

3.  Amount of time it takes light to reach the Earth from the Moon, in seconds.

4.  Amount of time it takes light from the Sun to reach Earth, in minutes

5.  Amount of time required for light to travel from the Sun to Pluto (40 AU from the Sun, on average) in hours

6.  How far light travels in one second (called 1 Light-Second, LS)

7.  How far light travels in one minute (LM)

8.  How far light travels in one year (LY)

9.  Distance to nearest star (other than Sun) - find the star and the distance (by looking it up)

10.  How many times around the Earth that a light pulse could travel in one second

11.  How many Moons across is the Earth?

12.  How many Earths across is the Sun?

13.  If you could travel at Earth's escape velocity (11,200 m/s), how long would it take you to reach the Moon?  How long would it take you to reach the nearest star (see 9 above)?

Interesting read

http://www.fromquarkstoquasars.com/worlds-with-two-stars-the-kepler-47-system/

Lab 1

LAB 1 - Time and Space

In this lab, you will investigate several ways of keeping time in the universe. Measuring the passing of astronomical time is by no means a trivial task - keep that in mind, as you find the current time according to various websites. This lab is structured as a series of topics, followed by questions and suggested websites. Have fun, and take your time!

Local Time

Give the current local time (whenever you are performing this lab).  Specify whether  we are on EST or EDT, and when (and how) this will change.

Interested in the time elsewhere? Try this:

http://www.timeanddate.com/worldclock/ 

Universal Time and Greenwich Mean Time

UT is counted from 0 hours at midnight, with unit of duration the mean solar day, defined to be as uniform as possible despite variations in the rotation of the Earth. Find the current UT. The clock applet below may be helpful:

http://tycho.usno.navy.mil/utclock.html

UT is very similar to Greenwich Mean Time (GMT), though this term is not used often these days. Both are 5 hours ahead of EST. Is this currently true? If not, why not?  What is the current GMT?

Longitude and Latitude

These quantities give the location on the surface of the semi-spherical Earth, by laying a grid atop it. Lines of longitude are measured with respect to the Prime Meridian. Find the longitude of your hometown: Lines of latitude are measured with respect to the equator. Find the latitude of your hometown.  Google maps may help.

Julian Date (JD)

Julian Day Number is a count of days elapsed since Greenwich mean noon on 1 January 4713 B.C., Julian proleptic calendar. The Julian Date is the Julian day number followed by the fraction of the day elapsed since the preceding noon.

Find the current JD:

Calendar

Which calendar do we currently use?

What calendar was this switched from, and when?

Why was the switch made?

Does all the world use the calendar we do? Explain.

Sidereal Time

ST is time based on duration of the Earth's rotation with respect to a point nearly fixed relative to the stars. Local Sidereal Time (LST) is computed from ST using a longitude correction. Find the current LST.

The Lunar and Solar Cycles

Have a look at sunrisesunset.com. Determine how the sunrise and sunset times change from day to day. Also determine how the moonrise and moonset times change daily.  What is the pattern, if there is one?

Eclipses
Locate a source of upcoming lunar and solar eclipses.  Answer these questions:

Where and when is the next total solar eclipse?
Where and when is the next total lunar eclipse?
When will be the next total solar eclipse visible in North America?  Will there be more than one total solar eclipse visible in North America in your lifetime?

Etcetera

Discuss any other times and/or calendars that are of interest to you.  Pick one calendar to discuss (at least in brief).

Celestial Sphere sites - have a look.

Celestial sphere sites

http://www.cascaeducation.ca/CSA/CSA_Astro9/files/multimedia/unit1/celestial_sphere/celestial_sphere.html

http://www.cascaeducation.ca/CSA/CSA_Astro9/files/multimedia/unit1/celestial_sphere/celestial_sphere.swf

http://astro.unl.edu/naap/motion3/animations/sunmotions.swf

http://www.astronomynotes.com/nakedeye/csph1t5.htm

http://www.astronomynotes.com/nakedeye/s4.htm

http://www.youtube.com/watch?v=8yCzzTkDSMo

Jack Horkheimer, for your interest.  Not related to the Celestial Sphere stuff.

Size and Structure - sites to check out and play with.

The size of things:

http://htwins.net/scale2/

http://scaleofuniverse.com/

http://xkcd.com/482/

Images to ponder

File under awesome / Van Gogh

http://www.richarddawkins.net/news_articles/2013/8/23/this-astronomer-recreated-starry-night-with-hubble-space-photos#

http://www.telegraph.co.uk/news/newstopics/howaboutthat/9355458/Dominoes-recreate-Vincent-van-Goghs-Starry-Night.html

And from "Quarks to Quasars" facebook feed:

Now, isn't this a brilliant image. This image was created by Alex Ruiz, a digital artists who creates his masterpieces in Photoshop. This picture is particularly special because it's a remake of the famous "Starry Night" painting by Van Gogh - a painting Neil deGrasse Tyson argues is one of the most influential paintings of all time.

The original Van Gogh painting is linked to below - you REALLY need to look at these two paintings side-by-side. The resemblance is fantastic.

Alex painted this from the same location as Van Gogh (though, maybe a slightly different vantage point. As Alex said, the original image is thought to have been painted from inside the sanitarium, but Alex didn't want bars on his image). This painting is a homage to Van Gogh which Alex says is one of his favorites. Von Gogh is the figure in the painting, "looking up at the night sky...probably in awe, as he wondered how he would capture the beauty he saw."

Alex was aiming for a painting that would be magical and inspiring while keeping a realistic feel to it. In my opinion, he couldn't have done a better job.

~Joshua

Image Credit: Alex Ruiz

Original Image: http://alexruizart.deviantart.com/art/Starry-Night-215823393

Van Gogh's Starry Night: http://uploads2.wikipaintings.org/images/vincent-van-gogh/the-starry-night-1889(1).jpg

You can purchase the image here: http://fineartamerica.com/featured/starry-night-alex-ruiz.html

Facebook page: https://www.facebook.com/alexruizdesign

Useful stuff.

FaceBook feeds:

From Quarks to Quasars

Sky and Telescope magazine

Science is Awesome

Useful Apps for smartphones or tablets:

Google Earth

Moon globe

Exoplanet

NASA

APOD

SkyWalk

Planets

SkyWeek

Distant Suns

Moon

Night Sky

Sky Map

Misc resources:

Astronomy magazine

Sky and Telescope magazine

In/around DC:

Smithsonian Air and Space Museum

Smithsonian Udvar-Hazy Air and Space Museum annex

Good sites (a very, very brief start):

http://www.heavens-above.com/

http://www.fromquarkstoquasars.com/

http://skymaps.com/

http://astronomy.com/

http://www.skyandtelescope.com/

sunrisesunset.com

http://www.galaxyzoo.org/

http://www.wechoosethemoon.org/

http://www.stargazing.net/naa/sotw.htm

Welcome to Astronomy! Now get out.

Hello friends.

Some time this weekend, do try to get outside and find the following objects (with the aid of your starchart).  Go to skymaps.com, if you need a new chart.

Here's the challenge.

Find these objects:

Big Dipper
Little Dipper
Polaris
Summer Triangle
Great square of Pegasus
Cassiopeia
Teapot (in Sagittarius)

Try to find the answers to the these questions (online):

How many constellations are there?
What are common asterisms?
What is the Northern Cross?

Enjoy!


http://skymaps.com/

This is a great place to go for free monthly star charts. This will give you really good, but approximate skyviews for nearly all uses. We will see later how to generate custom sky charts.

See also:

http://www.sunrisesunset.com/

to find out times for sunrise, sunset, moonrise, moonset - customized for your city.

For next class, investigate the celestial sphere. Bring a decent image or two.