satellite orbits added

earth-observation.html

@@ -157,6 +157,7 @@ <h3>Content</h3>
                   <li><a href="#application">Applications of Earth Observation</a></li>
                   <li><a href="#chalanges">Challenges and Future Directions</a></li>
                 </ul>
+                <li><a href="#orbits">Earth Satellite Orbits: A Celestial Ballet</a></li>
               <li><a href="#reference">Reference</a></li>
             </ol>
           </div>
@@ -230,7 +231,98 @@ <h4 id="chalanges">Challenges and Future Directions</h4>
         <p>Earth observation has transformed our understanding of the planet, providing valuable insights into environmental dynamics, natural hazards, and human activities. As technology continues to evolve, Earth observation will play an increasingly critical role in addressing global challenges and promoting sustainable development.</p>
 
 
+        <h3 id="orbits">Earth Satellite Orbits: A Celestial Ballet</h3>
+        Earth satellites, these artificial celestial bodies, dance around our planet in various orbits, each with its own unique purpose and characteristics. These orbits are determined by factors such as altitude, inclination, and eccentricity. Earth orbits can be devided into following three main categories: (for more details, please checkout <a href="https://www.esa.int/Enabling_Support/Space_Transportation/Types_of_orbits" target="_blank">Types of orbits</a>).
 
+        <div class="video-container">
+          <iframe width="560" height="315" src="https://www.youtube.com/embed/H-gaSnxP60A?si=rdI6CovZnC47Gi3A" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>
+          <p class="video-caption"><strong>Credit:</strong> <a href="https://www.youtube.com/watch?v=H-gaSnxP60A">Authors of the creator of the video</a>.</p>
+        </div>
+
+        <ol>
+          <li><strong>Low Earth Orbit (LEO): </strong>
+            <figure>
+              <img src="assets/img/remote-sensing/Low_Earth_orbit_pillars.png" alt="" style="max-width: 50%; max-height: auto;">
+              <figcaption style="text-align: center;"><strong>Credit: </strong><a href="https://www.esa.int/ESA_Multimedia/Images/2020/03/Low_Earth_orbit" target="_blank">ESA–L. Boldt-Christmas (ESA Standard Licence)</a></figcaption>
+            </figure>
+            <ul>
+              <li><b>Altitude:</b> Approximately 160-2,000 kilometers above Earth's surface   </li>
+              <li><b>Purpose:</b> Earth observation, scientific research, communications, and space stations   </li>
+              <li><b>Characteristics:</b> Short orbital periods (around 90 minutes), frequent passes over the same region, and low atmospheric drag.</li>
+            </ul>
+          </li>
+          <li><strong>Medium Earth Orbit (MEO): </strong>
+            <figure>
+              <img src="assets/img/remote-sensing/meo-orbit.png" alt="" style="max-width: 50%; max-height: auto;">
+              <figcaption style="text-align: center;"><strong>Credit: </strong><a href="https://www.ssc.spaceforce.mil/Newsroom/Article-Display/Article/3465697/leo-meo-or-geo-diversifying-orbits-is-not-a-one-size-fits-all-mission-part-2-of" target="_blank">Lisa Sodders, SSC Public Affairs</a>.</figcaption>
+            </figure>
+            <ul>
+              <li><b>Altitude:</b> Approximately 2,000-35,786 kilometers above Earth's surface.</li>
+              <li><b>Purpose:</b> Global navigation satellite systems (GNSS) like GPS, GLONASS, Galileo, and BeiDou</li>
+              <li><b>Characteristics:</b> Orbital periods of around 12 hours, suitable for providing continuous coverage over large areas. </li>
+            </ul>
+          </li>
+          <li><strong>Geostationary orbit (GEO): </strong>
+            <figure>
+              <img src="assets/img/remote-sensing/geostationary.gif" alt="Geostationary_orbit" style="width: 700px; height: auto;">
+              <figcaption style="text-align: center;"><strong>Credit: </strong><a href="https://www.youtube.com/watch?v=H-gaSnxP60A" target="_blank">Authors of the creator of the video</a>.</figcaption>
+            </figure>
+
+            <figure>
+              <img src="assets/img/remote-sensing/Geostationary_orbit_pillars.png" alt="" style="max-width: 50%; max-height: auto;">
+              <figcaption style="text-align: center;"><strong>Credit: </strong><a href="https://www.esa.int/ESA_Multimedia/Images/2020/03/Geostationary_orbit" target="_blank">ESA – L. Boldt-Christmas (ESA Standard Licence)</a>.</figcaption>
+            </figure>
+            <ul>
+              <li><b>Altitude:</b> Approximately 35,786 kilometers above Earth's surface</li>
+              <li><b>Purpose:</b> Communications, weather forecasting, and broadcasting.</li>
+              <li><b>Characteristics:</b> Orbital period of 24 hours, appears stationary from Earth's surface, ideal for providing continuous coverage over a specific region.</li>
+            </ul>
+          </li>
+
+        </ol>
+
+        <figure>
+          <img src="assets/img/remote-sensing/Geosynchronous.gif" alt="Geosynchronous orbits" style="width: 700px; height: auto;">
+          <figcaption style="text-align: center;"><strong>Credit: </strong><a href="https://www.youtube.com/watch?v=H-gaSnxP60A" target="_blank">Authors of the creator of the video</a>.</figcaption>
+        </figure>
+
+
+        We can also devide the earth orbits as follows:
+        <ol>
+          <li><strong>Polar orbit and Sun-synchronous orbit (SSO): </strong> Satellites in polar orbits usually travel past Earth from north to south rather than from west to east, passing roughly over Earth's poles.
+
+            <ul>
+              <li><strong>Polar orbits: </strong>
+                <figure>
+                  <img src="assets/img/remote-sensing/polarorbit.gif" alt="Polar_orbit" style="width: 700px; height: auto;">
+                  <figcaption style="text-align: center;"><strong>Credit: </strong><a href="https://www.youtube.com/watch?v=H-gaSnxP60A" target="_blank">Authors of the creator of the video</a>.</figcaption>
+                </figure>
+
+                <ul>
+                  <li><b>Inclination:</b> Approximately 90 degrees to the equator.</li>
+                  <li><b>Purpose:</b> Earth observation, remote sensing, and scientific research</li>
+                  <li><b>Height: </b>Polar orbits are a type of low Earth orbit, as they are at low altitudes between 200 to 1000 km.</li>
+                  <li><b>Characteristics:</b> Passes over both poles of Earth, provides global coverage, and is often used for weather forecasting and environmental monitoring.</li>
+                </ul>
+              </li>
+              <li><strong>Sun-synchronous orbit (SSO): </strong> Sun-synchronous orbits (SSOs) are a specific type of polar orbit where satellites pass over the Earth's poles while maintaining a constant position relative to the Sun. This means that a satellite in SSO always observes a particular location on Earth at the same local time, allowing for consistent comparisons over time. To ensure continuous sunlight, SSO satellites often orbit at dawn or dusk. This avoids shadows cast by the Earth and allows for uninterrupted observations. The typical altitude for SSO satellites is between 600 and 800 kilometers, and at 800 kilometers, they travel at approximately 7.5 kilometers per second.
+                <ul>
+                  <li><b>Inclination:</b> Approximately 97-99 degrees to the equator</li>
+                  <li><b>Purpose: </b>Earth observation, remote sensing, and scientific research</li>
+                  <li><b>Characteristics:</b> Passes over the same point on Earth at the same local time each day, ideal for studying seasonal variations and long-term trends.</li>
+                </ul>
+              </li>
+            </ul>
+            <figure>
+              <img src="assets/img/remote-sensing/Polar_and_Sun-synchronous_orbit_article.png" alt="" style="max-width: 50%; max-height: auto;">
+              <figcaption style="text-align: center;"><strong>Credit: </strong><a href="https://www.esa.int/ESA_Multimedia/Images/2020/03/Geostationary_orbit" target="_blank">ESA – L. Boldt-Christmas (ESA Standard Licence)</a>.</figcaption>
+            </figure>
+            <figure>
+              <img src="assets/img/remote-sensing/sunsynchronous.gif" alt="" style="max-width: 50%; max-height: auto;">
+              <figcaption style="text-align: center;"><strong>Credit: </strong><a href="https://www.youtube.com/watch?v=ylvgxNF3C0c" target="_blank">EUMESAT</a>.</figcaption>
+            </figure>
+          </li>
+        </ol>