**How Bright Are You?**

**ACTIVITY**

Use the data in the table found in the "**What CAN You See With a
Telescope?**" flashback to graph the **brightness** of the first ten
asteroids discovered versus the **dates of their discovery**.

If you are graphing this data *[by hand on graph paper]{.underline}*,
you will need to consider the following questions:

1.  What range in the brightness scale will you need for this graph?

2.  What time range will you need for this graph?

3.  Which of these variables---brightness or time---is the independent
    variable? On which axis---horizontal or vertical---should you plot
    the independent variable?

4.  Decide on the title of your graph. Print it at the top of the paper.

5.  Label your axes, including the units. Make sure that you have
    selected a range for both variables so that your plotted points take
    up at least half of the graph paper. The larger your graph, the
    easier it is to interpret.

6.  Plot the points but do [not]{.underline} connect the points with a
    line.

If you are *[using a spreadsheet]{.underline}* to graph this data, you
will first need to enter it into the spreadsheet. The first column
should contain the data and title for the dependent variable. Put the
title and data for the independent variable in the second column. You
will want to select a "scatter pattern" type of graph and follow the
directions for labeling the graph and the axes as given for your
particular spreadsheet.

Interpret your graph by answering the following questions.

1.  Describe the plots of your graph.

2.  What does the position of the points on your graph tell you about
    when the first asteroids were discovered?

3.  What is the relationship between the asteroid brightness and the
    time in which they were discovered? Remember that brightness is
    measured on a negative scale.

4.  The brightness scale is also exponential. For example, the
    difference in brightness between an asteroid with a brightness of 1
    is one hundred times as bright as an asteroid with a brightness of
    6, 5 magnitudes lower.

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a)  How much brighter is the brightest of the first group of asteroids
    than the dimmest of that group?

b)  How much brighter is the brightest of the second group of asteroids
    than the dimmest of that group?

c)  How much brighter is the brightest of all the asteroids than the
    dimmest of all the asteroids?

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5.  How do you think the differences in brightness related to
    astronomers' difficulty in finding the second group of new
    asteroids?

Use the data in the following table to graph the longest **size (km)**
of the first ten asteroids discovered versus the **dates of their
discovery**.

  ----------------- ----------------- ----------------- -----------------
  **Asteroid        **Year of         **Asteroid Name** **Size (km)**
  Number**          Discovery**                         

  1                 1801              Ceres             960

  2                 1802              Pallas            574

  3                 1804              Juno              190

  4                 1807              Vesta             560

  5                 1845              Astraea           119

  6                 1847              Hebe              185

  7                 1847              Iris              194

  8                 1847              Flora             90

  9                 1848              Metis             125

  10                1849              Hygeia            64
  ----------------- ----------------- ----------------- -----------------

6\. Size and brightness both played a part in the order and time of the
first ten asteroid discoveries. Which of these characteristics do you
think played the greatest part? Why do you think so?